Author: Byram W. Bridle
.
These vaccines have raised hopes that the pandemic is coming to an end. Hopefully this is true, but here are some catching points.
1. Long-term safety profile of COVID-19 vaccines
Because COVID-19 vaccines have received regulatory approval in record-breaking periods, these vaccines are distributed with unparalleled short safety profiles: only months worth of data are available.
The short-term safety of approved COVID-19 vaccines looks good. However, the induction of anaphylactic reactions in some vaccine recipients will not help optics for those with delayed vaccination. But these cases are rare and usually associated with severe allergies.
Twenty-three frail people in Norway have died shortly after receiving the Pfizer vaccine. The cause of these deaths is difficult to ascertain and may have had nothing to do with the vaccine. It has pressured physicians in that country to try to determine which members of this demographic are at high risk for COVID-19 mortality who should and should not be vaccinated.
If too many long-term invisible side effects build up over time, this could lead to a withdrawal of permission for vaccination.
2. Immunization duration of COVID-19 vaccines
Immunity period refers to how long a person is protected after receiving the vaccine. For previous vaccines, we could have reasonable confidence that immunity would last at least a few years before it was made public. COVID-19 vaccines have only a few months’ worth of immunosuppression.
If immunity decreases before ‘herd immunity’ is reached, people who have previously been vaccinated are more likely to become infected again and may spread out.
A man walks past the COVID-19 vaccination site at the Maimonides long-term care facility in Montreal. AN PRESS CANADIAN / Ryan Remiorz 3. Effectiveness of COVID-19 vaccines
There were public reports of more than 90 percent efficacy for Moderna and Pfizer vaccines. Unfortunately, Pfizer did not publicly reveal a large number of suspicious, but undiagnosed cases of COVID-19 that were excluded from measuring effectiveness. This was revealed in a summary report released by the U.S. Food and Drug Administration (FDA).
The data were revised with this new information reported by an associate editor of the British Medical Journal, which reported its findings that were not peer-reviewed in a comment column. the magazine. His estimate suggests the true effectiveness of the vaccine could be as low as 19 to 29 percent. This cannot be confirmed or denied until raw data not included in an FDA report are released.
The reported efficacy for the current Sinovac Biotech uncomplicated vaccine fell from 78 percent early in a clinical trial run in Brazil to 50.38 percent at the late stages of the trial. The cut-off for COVID-19 vaccine clearance is set at 50 percent effectiveness. If efficacy during public distribution becomes lower than ‘advertised’, COVID-19 vaccines perform lower than expected.
4. Risk of changes that may avoid immunity from vaccine
Several novel variants of SARS-CoV-2 have recently been identified. Coronaviruses replicate their genetic material in a way that tends to induce random mutations. If these mutations promote the survival of the virus in vaccinated people, it could be a catastrophe for the conventional immunization strategy.
Although the risk of immunosuppressive mutations cannot be accurately quantified, the administration of COVID-19 vaccines is likely to increase the likelihood of recurrence. this for at least two reasons. First, the conventional vaccines provide narrow-focus immunity aimed at a single viral spike protein. This means that SARS-CoV-2 only needs to suppress one protein to avoid immunization. In contrast, it would be more difficult for the virus if it had to convert several proteins to immunity.
Read more: The mink link: How COVID-19 mutations in animals affect human health and vaccine effectiveness
Second, the vaccination program is being rolled out in food fashion. This slow expansion of immunodeficiency among people surrounded by non-immune others provides the time and contact with a ‘reservoir population’ that a virus needs to generate random changes. their ability to catch vaccinated people could be investigated.
If a variable shows that his spike protein has been sufficiently altered to avoid vaccine – induced immunity, the release of the vaccine may fail. If this happens, vaccines may need to be regenerated to produce a new version of the spike protein, and it would be better if other proteins are added to extend immunity.
Importantly, acquiring natural immunity, which targets several components of the virus, may reduce the risk of re-infection with changes that may circumvent protein-specific spike immunity.
5. Unconfirmed COVID-19 vaccine regimens
Due to supply challenges for the distribution of dual-dose vaccines and with the aim of increasing the number and speed of vaccination, single-dose regimens, which are ‘a combination of vaccines from different manufacturers, and governments that change the times between doses.
Note that the effectiveness of Pfizer and Moderna vaccines lasts only a week or two after the second sight, and using the recommended interval and dose. The performance of vaccines cannot be guaranteed if they are administered differently from the way in which they have received regulatory approval. In fact, the results of a one-dose regimen with the Pfizer vaccine in Israel have been reported to be disappointing, although this is being debated.
The overall size and / or quality of the immune responses may be compromised by extending the interval between the two doses. Movements in protocols should not be accepted unless supported by clinical trial data.
Flock immunity without dispersal success? 
Registered nurse Sherry Plett celebrates after receiving a COVID-19 vaccine picture at the COVID-19 vaccine clinic at the Winnipeg Center for Health Sciences, December 16, 2020. THE CANADIAN PRESS / John Woods
Can herd immunity still be achieved if COVID-19 vaccines do not work? Probably! Climbing evidence shows that most people infected with SARS-CoV-2 have naturally acquired immunity that could protect them from re-infection. In fact, we have far more data for naturally acquired immunity than for vaccine-induced immunization against SARS-CoV-2.
There is even evidence that pre-existing immunity against other coronaviruses, including those that directly cause colds, may cross-protect some people against SARS-CoV-2. This is not surprising as this is what our immune system is designed to do. All of these people will contribute to gaining herd protection.
Read more: Can antibody tests tell us who is immune to COVID-19?
At the outset of the pandemic most governments decided not to use naturally acquired immunity as a primary means of providing herd immunity to give hospitals time to deal with serious illnesses. However, one year into the pandemic there is a big unanswered question: how close / far are we from herd natural immunity?
In Canada, we have done a poor job of monitoring this. An extensive antibody test would be a starting point. If someone has antibodies in their blood against SARS-CoV-2, then they were then at some point. If this were combined with the direct detection of SARS-CoV-2 performed at test centers, we could have a large data set at hand.
Natural immunity received by a growing number of people means that fewer people need vaccinations to reach herd immunity. As an advantage, natural immunity is also equivalent to broader immunity; these individuals should be more likely to be re-infected if an immuno-evasive SARS-CoV-2 reversal occurs.
Statistics Canada is beginning a large-scale study to conduct antibody tests on randomly selected Canadians. A smaller study by a researcher at the University of Toronto was started in June 2020. Data from these studies could be used to estimate the level of natural immunity in the general population. However, by simply looking for circulating antibodies against SARS-CoV-2 there appears to be a lack of immunity. These often disappear, but the B-memory cells they produce are usually permanent and can provide protection.
MENAFN10022021000199003603ID1101580999
Legal disclaimer: MENAFN provides the information “as is” without warranty of any kind. We take no responsibility or liability for the accuracy, content, images, videos, licenses, completeness, legality or reliability of the information contained in this article. If you have any complaints or copyright issues related to this article, please contact the provider above.