Filenews 7 June 2021
The New York Times summed up eight questions and answers that we know so far about the issue.
Many questions have been raised by scientists about the possibility of later needing booster or booster doses of covid-19 vaccines, but at present they do not have many answers.
Although many scientists in the US estimate that vaccines - at least those approved in their own country (Pfizer/BioNTech, Moderna, Johnson & Johnson) - will last for at least a year, in terms of the protection they provide against coronavirus, no one can yet be sure that this will be the case. It is also unclear whether the new variants of the virus, which are constantly appearing around the world, will bring new needs to the vaccination programme.
The U.S. National Institutes of Health recently launched a new clinical trial in fully vaccinated people to determine whether a booster dose will increase their antibodies and prolong immune protection. In any case, the scientists' sense is that we are still in uncharted waters with regard to booster doses.
The New York Times summed up eight questions and answers that we know so far about the issue:
Why do we have to have the flu vaccine every year, but do two doses of measles in childhood are enough to protect us for life?
Different pathogenic microorganisms affect our immune system in different ways. For diseases such as measles, cognition once leads to natural immunity for life. However, for other diseases (e.g. tetanus) the body's defences weaken over time and periodic supportive doses of vaccines (in the case of tetanus per decade) are needed. In addition, some viruses, such as influenza, change themselves rapidly, which is why they require a new vaccine every year.
How are Covid-19 vaccines compared to others in terms of protection?
We can't be sure, as people started getting massively vaccinated against the coronavirus just a few months ago. Nor could their previous clinical trials show what immune protection would be a year later. However, the first signs are encouraging, as - based on studies so far - antibody levels against coronavirus appear to be dropping slowly, so vaccination immunity may remain strong for some time (still unknown how much). Those infected with the virus and then also had the vaccine may have longer-term protection., perhaps for years, but this needs to be confirmed.
Can some Covid-19 vaccines last longer than others?
probably. Scientists have already found that mRNA vaccines (Pfizer/BioNTech and Moderna) are somewhat more effective than more traditional vaccines based on an inactivated virus. However, mRNA vaccines are relatively new and therefore the duration of their protection has not been studied in the long term. However, it is likely that protection against less effective vaccines will also take less time.
How do we know when vaccines will lose their effectiveness?
Scientists are looking - through ongoing studies - for biomarkers that will reveal when immune protection after a vaccine will no longer be enough to "brake" the coronavirus. Probably a level of antibodies in the blood will be the "threshold" under which someone vaccinated will again be at risk of being infected and sick with Covid-19.
What about variations and mutations?
We'll probably need booster doses to block the new usually more contagious variants of coronavirus, but that's not yet clear. However, the emergence of new variants has accelerated the relevant studies on booster doses. Scientists cannot rule out that new variants with greater resistance to existing vaccines will appear in the coming months.
Are we going to need a specific booster dose for a specific variant?
It remains unclear yet. Some scientists suspect that a strong immune response of the organism to the original ("Chinese") variant of coronavirus will provide adequate protection against both the then variants. On the other hand, it is also possible that a vaccine specifically designed against a particular variant will be more effective. Pfizer has begun testing both cases: some volunteers who have already been fully vaccinated will make a third dose of the same vaccine, while other volunteers will make a newer experimental vaccine against beta variants ("South African"). A company spokesperson said that "based on what we know so far, our current view is that until we see a decrease in the circulation of SARS-CoV-2 and Covid-19 disease, we consider it likely that a third booster dose of our vaccine, within 12 months of its administration, will perhaps be necessary to help protect against Covid19."
Will I be able to change the vaccine when I do a booster dose?
perhaps. Research into previous diseases has shown that mixing different vaccines can enhance protection. Studies of a combination of vaccines against Covid-19 are ongoing and will confirm whether this is the case with coronavirus.
What about those who haven't even done the first dose?
Let them prepare for the prospect that it will take three rather than two doses.
