CORONAVIRUS VACCINE COMPARISON

CORONAVIRUS VACCINE COMPARISON

Coronavirus Vaccine Comparison – All of vaccines are typically need years for research and testing before it can be used clinically. But some of situation not required that because of emergency state happen in this pandemic era of Corona virus. The emergency of needing the vaccine as one of the prevention step to stop the spreading of the virus so each country developed their own research to make the best vaccine to help their own country and to help our world so we can fight and stand against the COVID-19 together.

So many vaccines are developed in each country around the world. But not all the vaccines are ready to be used. Researchers are currently testing 67 vaccines in clinical trials on humans, and 20 have reached the final stages of testing. At least 89 preclinical vaccines are under active investigation in animals. Some of us maybe didn’t understand about clinical trials, vaccine trials etc. But here some of the information about coronavirus vaccine comparison.1

Also Read COVID-19 and DIABETES

I. The Vaccine Testing Process

An ideal SARS-CoV-2 vaccine, to fight the pandemic, should have the following features:2

  1. Elicit long-lasting protective immune responses;
  2. Should be given to everyone regardless of comorbidity or age, immune status, pregnancy/breastfeeding status;
  3. Lack the potential to cause antibody dependent enhancement (ADE) or pulmonary immunopathology;
  4. Should be thermostable in order to enable transportation and storage in developing countries with poor refrigeration facilities;
  5. Be highly immunogenic in the general population including a population with preexisting anti-vector antibodies.

An experimental vaccine is first tested in animals to evaluate its safety and potential to prevent disease. It is then tested in human clinical trials, in three phases:

  • Phase I – in phase I, the vaccine is given to a small number of volunteers to assess its safety, confirm it generates an immune response, and determine the right dosage.
  • Phase II – in phase II, the vaccine is usually given hundreds of volunteers, who are closely monitored for any side effects, to further assess its ability to generate an immune response. In this phase, data are also collected whenever possible on disease outcomes, but usually not in large enough numbers to have a clear picture of the effect of the vaccine on disease. Participants in this phase have the same characteristics (such as age and sex) as the people for whom the vaccine is intended. In this phase, some volunteers receive the vaccine and others do not, which allows comparison to be made and conclusions drawn about the vaccine.
  • Phase III – in phase III, the vaccine is given to thousands of volunteers – some of whom receive the investigational vaccine, and some of whom do not, just like in phase II trials. Data from both groups is carefully compared to see if the vaccine is safe and effective against the disease it is designed to protect against.

Once the results of clinical trials are available, a series of steps is required, including reviews of efficacy, safety, and manufacturing for regulatory and public health policy approvals, before a vaccine may be introduced into a national immunization program.3

Early or Limited Approval : many countries have given emergency authorization from their government based on preliminary evidence that they are safe and effective.1

Approval : regulators review complete trial results and plans for vaccine’s manufacturing, and decide wheter to give it full approval.1

Combined Phase : one way to accelerate vaccine development is to combine phases. Some vaccines are now in Phase ½ trials, for example, which this tracker would count as both Phase 1 and Phase 2.1

Paused or Abandoned : if investigation observe worrying symptoms in volunteers, they can pause the trial. After an investigation, the trial may resume or be abandoned.1

II. CORONAVIRUS VACCINE COMPARISON

Table 1. Lead SARS-Cov-2 candidate vaccines with EUA granted, in phase III trials, or licensed (prior to phase III trials)3.

coronavirus vaccine comparison

φ Storage or transportation temperature. * SU not defined in trial. A amount of 3 µg was proposed for a phase III trial [30]. 1x = 1 immunization. 2x = 2 immunizations. VP = virus particles. NA = not applicable. ** Phase I/II studies used two different doses: 5×1010 and 1×1011 virus particles [31]. *** Phase I/II studies used 1×1011 virus particles/dose [32]. # Two versions are available: a frozen version and a lyophilized version, Gam-COVID-Vac-lyo, to be reconstituted. % Approved for use in Chinese military. € Approved for use in Russia. ∑ EUA granted. $ NAAT = nucleic acid amplification test.

coronavirus vaccine comparison
coronavirus vaccine comparison
NOCOMPANYVACCINE NAME
1.Pfizer(New York) and BIONTECH (German)Comirnaty (also known as tozinameran or BNT162b2
2.Moderna(Boston) and National Institute of HealthmRNA-1237
3.AstraZaneca(Swedish company) and University of Oxford (England)AZD1222 (also known as Covishield in India )
4.Gamaleya Research Institute (Russia)Sputnik V (also known as Gam-Covid-Vac)
5.Sinovac Biotech (China)CoronaVac (formerly PiCoVacc)
6.Johnson & Johnson/JensenAd26.COV2.S
7.NovavaxNVX-CoV2373
Coronavirus vaccine comparison by name.
  1. Pfizer-BioNTech4

The Pfizer-BioNTech COVID-19 vaccine was sent to the FDA for possible Emergency Use Authorization (EUA) on Friday, November 20 and authorized on December 11. It is an mRNA vaccine that codes for the virus’s spike protein and is encapsulated in a lipid nanoparticle. Once injected, the cells churn out the spike protein, triggering the body’s immune system to recognize the virus. In Phase III trials, it demonstrated 95% efficacy. The Pfizer-BioNTech vaccine requires storage at about -94 degrees F, which requires specialized freezers.

Type: mRNA

Doses: 2, 21 Days Apart

EUA Date: December 11, 2020

Price: $19.50 per dose for first 100 million doses

Efficacy: About 95%

Status: Approved in Several Countries-Emergency use in U.S, and elsewhere

2. Moderna

On November 16, Moderna issued a preliminary data readout out of its COVID-19 vaccine, suggesting an efficacy rate of 94.5%. It was authorized by the FDA on December 19. Like the Pfizer-BioNTech vaccine, it is an mRNA vaccine. Unlike that vaccine, however, the Moderna vaccine is stable at 36 to 46 degrees F, about the temperature of a standard home or medical refrigerator, for up to 30 days and can be stored for up to six months at -4 degrees F. It is expected to go to the FDA for consideration for an EUA within days.

Type: mRNA

Doses: 2, 28 Days Apart

EUA Date: December 18, 2020

Price: $25-$37 per dose

Efficacy: About 95%

Status: Approved in Switzerland, Emergency use in U.S., E.U., Elsewhere

3. AstraZeneca-University of Oxford

On November 23, AstraZeneca and the University of Oxford announced high-level results from an interim analysis of their COVID-19 vaccine, AZD1222. The analysis was from the trials in the UK and Brazil and demonstrated efficacy of up to 90%. The vaccine was effective at preventing COVID-19, with no hospitalizations or severe cases in people receiving it. There were a total of 131 COVID-19 positive cases in the interim analysis group. One dosing regimen was given at a half dose and demonstrated 90% efficacy, followed by a full dose at least one month apart. Another dosing regimen demonstrated 62% efficacy when given two full doses at least one month apart. The combined analysis showed average efficacy of 70%. The AstraZeneca vaccine can be stored, transported and handled at normal refrigerated conditions, about 36-46 degrees F for at least six months and administered within existing healthcare settings.

The AstraZeneca and University of Oxford’s vaccine uses technology from an Oxford spinout company, Vaccitech. It deploys a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees. It contains the genetic materials of the spike protein. After vaccination, the cells produce the spike protein, stimulating the immune system to attack the SARS-CoV-2 virus.

Type: Adenovirus-based

Doses: 2, 28 Days Apart

Likely EUA Date: Authorized in Europe on January 12, 2021, and other countries, but unlikely in the U.S. until spring

Price: $25-$37 per dose

Efficacy: Currently about 70% overall

Status : Emergency use in Britain, E.U., Elsewhere 

4. Russia’s Sputnik V Vaccine

Around November 11, Russia’s National Research Center for Epidemiology and Microbiology, which Russia authorized for use in August ahead of even beginning a Phase III trial claimed had an efficacy rate of 92% after the second dose. It was based on a first interim analysis 21 days after the first injection during the ongoing Phase III study. On November 24, the organization claimed 95% efficacy based on new preliminary data. On December 14, 2020, they reported efficacy of 91.4%. It also offered to share one of its two human adenoviral vectors with AstraZeneca to increase the efficacy of the AstraZeneca vaccine.

Russia’s Gamaleya research institute appears to be focused on potentially marketing their vaccine worldwide. Even the name of the vaccine has emphasized the idea of a race. The organization has indicated a dose of the vaccine will cost no more than $10, about half the cost of the Pfizer vaccine. The organization has also predicted they could produce 1 billion doses in the next year. At this time, aside from Russia, it will potentially be sold in India, Korea, Brazil, China, and Hungary. The Hungarian government is the only European Union country to express interest to date.

Type: Adenovirus-based

Doses: 2

Likely EUA Date: Not applicable in the U.S.

Price: $10 per dose

Efficacy: 91.4%

Status: Early use in Russia, Emergency use Elsewhere

5. Sinovac Biotech

On January 13, 2021, China-based Sinovac Biotech reported that its COVID-19 vaccine had a 50.38% efficacy in late-stage clinical trials in Brazil. The company’s clinical trials are demonstrating dramatically varying efficacy rates. In Indonesia, a local trial demonstrated an efficacy rate of 65%, but the trial had only 1,620 participants. Turkey reported an efficacy rate of 91.25% in December 2020. Another trial in Brazil run by a local partner, Butantan Institute, reported last week a 78% efficacy rate in mild cases while 100% against severe and moderate infections. It is an inactivated vaccine that uses inactivated SARS-CoV-2 viruses.

Type: Inactivated SARS-CoV-2 virus

Doses: 2

Likely EUA Date: Not applicable in the U.S.

Price: $13,6 (Indonesia)5

Efficacy: 50.38% to 91.25%, depending on the clinical trial

Status: Approved in China, Emergency use Elsewhere

6. Johnson & Johnson

Johnson & Johnson announced on November 15 that it initiated a second global Phase III trial of its Janssen COVID-19 vaccine. They expect to enroll up to 60,000 volunteers worldwide.

Whereas all of the other three vaccine candidates require two doses about 28 days apart, the J&J vaccine only requires a single dose. Interim results from its Phase I/IIa trial demonstrated a single dose of the vaccine induced a robust immune response and was generally well-tolerated. The ENSEMBLE 2 study evaluated a two-dose regimen as well.

The vaccine uses the company’s AdVac technology platform, which it used to develop its approved Ebola vaccine and its Zika, RSV and HIV investigational vaccine candidates. It revolves around the use of an inactivated common cold virus, similar to what the AstraZeneca-University of Oxford program utilizes.

On February 4, Johnson & Johnson announced that it has filled for an emergency use authorization in the U.S. The FDA has scheduled a meeting of the committee that makes vaccine recommendations on February 26, and a decision could follow shortly afterward.  

Type: Adenovirus-based

Doses: 1

Likely EUA Date: Possibly March or April 2021

Price: $10 per dose

Efficacy: 72% in the U.S., 66% overall, 85% for preventing severe disease 

Status: Phase 3

7. NOVAVAX

Maryland-based Novavax makes vaccines by sticking proteins onto microscopic particles. They’ve taken on a number of different diseases this way; their flu vaccine finished Phase 3 clinical trials last March. The company launched trials for a Covid-19 vaccine in May, and the Coalition for Epidemic Preparedness Innovations invested $384 million to support research on the vaccine. In July the U.S. government awarded Novavax another $1.6 billion to support the vaccine’s clinical trials and manufacturing.

On January 28, 2021, Novavax announced that its COVID-19 vaccine, NVX-CoV2373, hit the primary endpoint with a vaccine efficacy of 89.3% in its Phase III trial in the UK. The vaccine is a protein-based COVID-19 vaccine candidate. It also has data from the South Africa Phase IIb trial and several Phase I, II and III trials. It has demonstrated high clinical efficacy against the UK and South Africa variants as well.

The vaccine contains a full-length, prefusion spike protein made using the company’s recombinant nanoparticle technology and its proprietary saponin-based Matrix-M adjuvant. It is stable at 2 to 8 degrees C and shipped in a ready-to-use liquid formulation.

Type: Protein-based vaccine

Doses: 2

Likely EUA Date: Possibly in March or February 2021 in the UK; possibly Q1 2021 or later in the U.S.

Price: $16 in the US

Efficacy: 89.3%

That’s it. The article about Coronavirus Vaccine Comparison. If you like to see another article, please follow the link below.

Also Read Delaying second dose of coronavirus vaccines is ‘risky gamble’: according to experts

Coronavirus Vaccine Comparison

REFFERENCES

  1. Carl Zimmer, Jonathan Corum, Sui-Lee Wee. Coronavirus Vaccine Comparison Tracker.2 February 2021. https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html?auth=link-dismiss-google1tap
  2. Gregory A.Poland, MD; Inna G. Ovsyannikova, PhD; Stephen N.Crooke. SARS-CoV-2 Vaccine Development: Current Status. 2020. Mayo Clinic. Access: 6 February 2021. https://doi.org/10.1016/j.mayocp.2020.07.021
  3. WHO. Vaccines and Immunization: What is vaccination?. Access: 4 February 2021.  https://www.who.int/news-room/q-a-detail/vaccines-and-immunization-what-is-vaccination?adgroupsurvey={adgroupsurvey}&gclid=CjwKCAiA9vOABhBfEiwATCi7GA4Q0gma7eld7lLLdXFkF64O_a9BqrMusUos10__fOldtUZX9fbpfhoCpxAQAvD_BwE)
  4. Mark Terry. UPDATED Comparing COVID-19 Vaccines: Timelines, Types and Prices. Access: 4 February 2021. https://www.biospace.com/article/comparing-covid-19-vaccines-pfizer-biontech-moderna-astrazeneca-oxford-j-and-j-russia-s-sputnik-v/
  5. Milton Lum, Dr. Covid-19 Vaccine Prices. Code Blue, Health is Human Right. December 2020. Access : https://codeblue.galencentre.org/2020/12/25/covid-19-vaccine-prices/ 16 February 2021
Things People With Diabetes Must Know About the COVID-19 Vaccines

Things People With Diabetes Must Know About the COVID-19 Vaccines

Things People With Diabetes
Source : Everydayhealth

People with diabetes are at a higher risk of developing complications of COVID-19, making it all the more important that they are vaccinated against the disease as soon as possible.

It’s a new year, and COVID-19 vaccines offer hope for those wanting to protect themselves, especially people with underlying health conditions such as diabetes.

You may have questions about these new vaccines, including when you can get them and what questions you should ask your doctor about them. Experts we talked with say the vaccines are safe, effective, and important for people with diabetes.

“The most important thing is that people with diabetes get vaccinated as soon as it becomes available to them,” says Robert Gabbay, MD, PhD, chief science and medical officer for the American Diabetes Association (ADA) in Arlington, Virginia.

Also Read Covid-19 Vaccine Updates

1. When Will I Be Able to Get the Vaccine if I Have Diabetes?

It depends on where you live. At a federal level, the Centers for Disease Control (CDC) makes recommendations about who should receive priority for vaccination. It is then up to each state to use those recommendations to plan for and distribute vaccines to counties and residents.

Even so, guidelines are changing. In mid-January, U.S Health and Human Services (HHS) Secretary Alex Azar said Americans 65 years and older and those who are younger but have underlying health conditions should receive priority, as AARP reports.

If your state is following the CDC’s recommendations, healthcare workers and nursing home residents are receiving first priority for the vaccine. Next, the CDC recommends vaccinating frontline workers such as firefighters, teachers, and grocery store workers, along with people over 75.

Then, the CDC recommends vaccinating people with type 2 diabetes and other underlying medical conditions due to their increased risk of severe COVID-19-associated illness.

People with type 1 diabetes do not currently have the same priority vaccination with the CDC. But groups including the Juvenile Diabetes Research Foundation (JDRF) and the ADA are advocating for this priority at a federal and state level.

Justin Gregory, MD, assistant professor of pediatrics at Vanderbilt Children’s Hospital in Nashville, who has type 1 diabetes, says that people with type 1 diabetes should have the same priority for vaccination as people with type 2 diabetes because both groups have a similarly increased risk for dangerous and deadly COVID-19 illness. 

In the end, states make their own decisions about vaccination priority, so check your state and local health department’s website to find out when you are eligible. The ADA has also assembled links to individual states’ vaccination plans as part of its COVID-19 Vaccination Guide.

2. Does Having Another Health Condition With Diabetes Affect My Place in Line?

Potentially. The CDC notes notes that the risk for hospitalization increases with the more “high-risk” medical conditions a person has — it’s 2.5 times for a person with one condition and 5 times for people with three or more conditions. Nevertheless, having comorbidities, such as heart and kidney disease, does not mean you will be allowed to get vaccinated before someone with only diabetes or another single health condition. Again, it comes down to where you live.

In Massachusetts, for example, people with two or more underlying conditions are prioritized to get a COVID-19 vaccine before those with only one condition. Other states do not designate priority by the number of underlying medical conditions.

3. Are COVID-19 Vaccines Free for People With Diabetes?

The COVID-19 vaccine is free for everyone, regardless of diabetes status, according to the CDC. However, some providers administering the vaccine may charge a fee, which can be reimbursed by your public or private health insurance, or by the Health Resources and Services Administration’s Provider Relief Fund if you do not have insurance.

4. Why Is It Important to Get the Vaccine if You Have Diabetes?

“It’s quite clear that people with diabetes do much worse than people without diabetes in terms of their outcomes with COVID,” says Dr. Gabbay. Early in the pandemic, a study from the CDC found that roughly half of people who died from COVID-19 under age 65 had diabetes. 

The protective effects of vaccines are critical for people with diabetes who are at increased risk for severe and deadly infection from COVID-19, says Dr. Gregory. His December 2020 study in Diabetes Care found that people with type 1 or type 2 diabetes are 3 times more likely to be hospitalized or experience severe COVID-19 illness compared with people without diabetes. 

Two studies from the United Kingdom showed similar risk. An October 2020 study in The Lancet Diabetes & Endocrinology found that people with type 1 or type 2 diabetes were 2 to 3 times more likely to die from COVID-19 in the hospital than people without diabetes. And a December 2020 study in The Lancet Diabetes & Endocrinology found that people with type 1 or type 2 were more likely to die or to be treated in the intensive care unit for COVID-19.

5. Are the Vaccines Safe and Effective for People With Diabetes?

Two COVID-19 vaccines are currently available in the United States — and people with diabetes were included in both the vaccine trials. Both require two doses spaced either 21 days (Pfizer-BioNTech vaccine) or 28 days (Moderna vaccine) apart. With their two doses completed, these vaccines are over 90 percent effective and received emergency use authorization from the U.S. Food and Drug Administration (FDA) in December 2020.

“We wanted to make sure we recruited a number of individuals who had the types of underlying medical conditions that can make COVID more severe,” says C. Buddy Creech, MD, MPH, director of the Vanderbilt Vaccine Research Program in Nashville and part of the phase 3 trials of the Moderna COVID-19 vaccine.

That included people with diabetes, hypertension, and obesity, says Dr. Creech. People with type 1, type 2, and gestational diabetes were included in the Moderna clinical trial, he adds. The FDA filing from Pfizer-BioNTech says the trial included but does not specify among types.

The vaccines were well-tolerated, highly efficacious, and elicited an immune response in people with underlying conditions, such as diabetes, says Creech.

“People with diabetes are going to be prioritized [for COVID-19 vaccination] because we know they’re at increased risk for disease. And they should feel confident that someone a whole lot like them was enrolled in the clinical trial so that we can say with a greater degree of certainty that they can effectively get this vaccine,” says Creech.

Gabbay says that the data do not suggest the COVID-19 vaccines pose particular risk for people with diabetes. He also says there is no reason to think there would be interactions with insulin or other medications that people with diabetes might take.

6. What Side Effects of the Vaccine Should People With Diabetes Pay Attention To?

In general, the most common side effects of both vaccines are pain, swelling, and redness at the injection site. Other common side effects are chills, tiredness, and headaches. Most of these side effects were mild, but some people had more severe reactions that interfered with daily activities.

Gabbay says side effects of the COVID-19 vaccines are similar to those of flu vaccines. For someone living with diabetes, keeping a sick-day kit with extra medications and supplies is beneficial in case you do not feel well.

7. What Questions Should People With Diabetes Ask Their Healthcare Teams About the COVID-19 Vaccines?

Gabbay says the first question patients should ask their providers about the COVID-19 vaccine is, “When can I get it?”

Be proactive in calling your provider to ask for the vaccine, says Gabbay. Check the websites of your state and local health departments to find out about local vaccine distribution. “Being patient, persistent, and informed is the best approach,” says Gabbay.

REFERENCES :

  1. Everydayhealth.com
  2. By Kate Ruder Medically Reviewed by Justin Laube, MD

How Effective is a Single Vaccine Dose Against Covid-19 ?

How Effective is a Single Vaccine Dose Against Covid-19 ?

Single Vaccine Dose, How Effective it is ? – The cases are already beginning to emerge.

When 85-year-old Colin Horseman was admitted to Doncaster Royal Infirmary in late December, it was for a suspected kidney infection. But not long afterwards he caught Covid-19 – at the time, roughly one in four people in hospital with the virus had acquired it there. He developed severe symptoms and was eventually put on a ventilator. A few days later, he died.

At first glance, Horseman’s situation may seem fairly typical, though no less tragic for it. After all, at least 84,767 people have now succumbed to the disease in the UK alone at the time of writing. But, as his son recently explained in a local newspaper, less than three weeks earlier he had been among the first people in the world to receive the initial dose of a Covid-19 vaccine – the Pfizer-BioNTech version. He was due to receive the second dose two days prior to his death.

In fact, most vaccines require booster doses to work.

Take the MMR – measles, mumps and rubella – vaccine, which is given to babies around the world to prevent these deadly childhood infections. Around 40% of people who have received just one dose are not protected from all three viruses, compared to 4% of those who have had their second. People in the former group are four times more likely to catch measles than those in the latter – and there have been outbreaks in places where a high proportion of people have not completed the full MMR vaccination schedule.  

“The reason that people are so keen on boosters and consider them so vital is that they kind of send you into this whole other kind of fine-tuning mode of your immune response,” says Danny Altmann, professor of immunology at Imperial College London.

Also Read Covid-19 Vaccine Updates

How Booster Vaccines Work

When the immune system first encounters a vaccine, it activates two important types of white blood cell. First up are the plasma B cells, which primarily focus on making antibodies. Unfortunately, this cell type is short-lived, so although your body might be swimming in antibodies within just a few weeks, without the second shot this is often followed by a rapid decline.

Then there are the T cells, each of which is specifically tailored to identify a particular pathogen and kill it. Some of these, memory T cells, are able to linger in the body for decades until they stumble upon their target – meaning immunity from vaccines or infections can sometimes last a lifetime. But crucially, you usually won’t have many of this cell type until the second meeting. 

The booster dose is a way of re-exposing the body to the antigens – the molecules on pathogens that trigger the immune system. “So, once you’ve had your boost you’ll have a higher frequency of memory T cells and ditto to some extent for the size of the pool of memory B cells you’ll have. They’ll also be making higher quality antibodies.”

On second exposure to the same vaccine or pathogen, the B cells that remain from before are able to rapidly divide and create a menacing throng of descendants, leading to a second spike in the amount of antibodies circulating.

The second dose also initiates the process of “B cell maturation”, which involves selecting the immature ones with the best receptors for binding to a particular pathogen. This happens while they’re still in the bone marrow – where white blood cells are made – and afterwards they travel to the spleen to finish developing. This means B cells are not only more numerous afterwards, but the antibodies they produce are better targeted.

Memory T cells, meanwhile, also proliferate rapidly. They’re already thought to have played a critical role during the current pandemic, protecting some people from developing severe Covid-19. Though the virus may have only been circulating globally since around December 2019, there’s some evidence they may have “seen” other coronaviruses before, such as those that cause the common cold – allowing them to recognize Covid-19.

REFERENCES :

  1. https://www.bbc.com/future/article/20210114-covid-19-how-effective-is-a-single-vaccine-dose

Delaying second dose of coronavirus vaccines is ‘risky gamble’: according to experts

Delaying second dose of coronavirus vaccines is ‘risky gamble’: according to experts

Delaying second dose of coronavirus vaccines is ‘risky gamble’: according to experts

Amid shortages in coronavirus vaccine supplies, some Canadian provinces have decided to delaying second dose of coronavirus, which experts have called a “risky approach” and “a gamble.”

Ontario’s government announced on Saturday that long-term care residents, staff and essential caregivers who have received their first doses of the Pfizer-BioNTech vaccine will now get the second jab within 21 to 27 days. Everyone else will receive their second dose after three weeks but before 42 days.

The time span between doses specified by Pfizer and BioNTech is 21 days.

This comes in the wake of a temporary delay in shipments of the Pfizer vaccine to Canada as the company is scaling up its European manufacturing capacity.

Last month, British Columbia said it was changing its second-dose schedule for both Pfizer and Moderna’s vaccines to 35 days to allow giving the first doses to as many people as possible right away. Moderna’s second booster shot is supposed to follow the first by 28 days.

Meanwhile, Quebec is pushing the time between the two doses to a maximum of three months in an attempt to vaccinate more seniors faster with a first injection.

These timeline changes have raised concerns and questions about the impact this may have on the effectiveness of the vaccines.

“There is a risk in this approach,” said Dr. Alberto Martin, professor of immunology at the University of Toronto.

It’s possible that a large fraction of these individuals will not develop full immunity and thereby waste many of these doses,” he told Global News.

While there is a buffer and wiggle room for a few days and weeks between vaccine doses, experts have cautioned against significant delays that deviate from the prescribed time period used in the clinical trials.

“The longer you spaced that interval, the higher risk (of) … maybe not getting the full immune response possible,” said Dr. Zain Chagla, an infectious diseases physician at St. Joseph’s Healthcare in Hamilton, in an interview with Global News.

However, since this is an experiment with no sufficient data, it still remains unclear what the exact impact of the delay will be, both Chagla and Martin said.

The World Health Organization (WHO) has advised that in case of shortages in vaccine supplies, the second Pfizer dose can be extended to up to six weeks or 42 days after the first, which is what Canada’s National Advisory Committee on Immunization (NACI) has also recommended.

Currently, there is no data on the maximum interval between doses or on medium- or long-term efficacy of COVID-19 vaccines, according to NACI.

NACI experts say delaying second dose of coronavirus up to six weeks, instead of three or four, could more quickly get at least some protection against COVID-19 to more people.

The United Kingdom, where a new, more contagious variant of COVID-19 began spreading last month, has gone against the advice of the drugmakers, as well as WHO, and delayed the second dose of Pfizer and AstraZeneca’s vaccine by up to 12 weeks.

The United States, meanwhile, is taking a different approach and sticking with the originally specified timeframe of 21 days between Pfizer’s shots and 28 days for Moderna.

In a statement on its website, the U.S. Food & Drug Administration says changes in the schedules of vaccine administration without appropriate supporting data can pose a “significant risk of placing public health at risk” and “undermining the historic vaccination efforts.”

Also Read What are the differences of these various COVID-19 vaccines?

Prioritizing The Elderly

When there is an unstable supply chain, most experts agree that the priority should be to give the elderly and long-term care residents the two doses on time.

Dr. Isaac Bogoch, an infectious disease physician at Toronto General Hospital, said the focus in Ontario is to put all the resources into vaccinating those who are most vulnerable and at greatest risk of death.

We know that people in long-term care are typically older or have other health problems, (yet) are just less likely to mount the same immune responses as otherwise healthier, younger individuals. So, the goal is really to give those two vaccine doses as per that schedule to those who live in long-term care. I think that’s very reasonable,” he told Global News.

As for the rest of the population, provinces should not purposely delay the second dose beyond the 42-day mark, he added.

“That 42 days is the maximum, it’s not the goal, … and if people can be closer to that day 21 goal, the better,” Bogoch said.

According to recent modelling data from researchers at the University of Toronto, administering most of Canada’s coronavirus vaccines now, as opposed to reserving half of them to be used later as second doses for the first recipients, could prevent a significant amount of new symptomatic COVID-19 infections.

Dr. Anna Banerji, an infectious disease specialist at the University of Toronto, said it is actually better to spread the vaccine to as many people as quickly as possible with a first dose rather than reserving the second shot in case of shortages.

“If the end goal is to save lives and prevent hospitalization and vulnerable populations, then it’s better to get the vaccine out to all the people who are at high risk, like long-term care facilities, first rather than getting two to half the amount of people,” she told Global News.

REFERENCES :
1. https://globalnews.ca/news/7585267/coronavirus-vaccine-second-dose-delay/

2. Saba Aziz