Pfizer SARS-CoV-2 vaccine effective from day 11 after 1d vaccine

A new study from a team of Australian scientists suggests that the second ‘booster’ dose of the Pfizer-BioNTech vaccine may not increase vaccine efficacy against severe respiratory syndrome (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID -19).

The findings suggest that a single dose of the vaccine may be sufficient to provide a strong immune response 11 days after vaccination.

The findings could help shape policy as vaccine distribution has been slow in countries such as the United States and Canada. This could also increase with vaccine circulation efforts in developing countries where supply has been scarce.

This opens up opportunities where quick short-term protection can be used for ‘ring fencing’ vaccines after a revolution or browser. Also, it could be given to passengers in the fortnight before their planned trip. As there has been no immediate improvement in the administration of the second vaccine after 3 or 4 weeks it also increases the ability to administer a single dose (at least in the short term when supply is scarce) and give health services more flexibility in providing vaccines and in a second dose if proven necessary. ”

The study “Reanalysis of Pfizer mRNA BNT162b2 SARS-CoV-2 vaccine data does not find greater efficacy after the increase: Implications for vaccine policy and our understanding of the mode of action” available as a preview of the medRxiv* server, while the article is under peer review.

How they did it

The research team repeated Pfizer-BioNTech phase III test data from day 1 to 111 in the placebo and experimental groups. They also looked at data from the Moderna vaccine trial. However, since the numbers of COVID-19 cases in the Moderna test were low in the first few weeks, they did not have enough data to assess it. Instead, Moderna test data was used for comparison purposes with Pfizer test data.

They examined the efficacy of vaccines from day 11 to day 28 and compared the efficacy of the second vaccine dose delivered on day 28 up to day 111.

The Pfizer vaccine shows full effectiveness 11 days after vaccination

Results showed that the Pfizer-BioNTech mRNA vaccine provided a strong immune response 11 days after the first vaccine dose. They also found that the second vaccine did not help increase efficacy.

In particular, the first dose of vaccine helped to develop neutralizing antibodies detected before the second dose.

Although the Moderna sample size was limited, compared with the Pfizer-BioNTech mRNA vaccine, there was no significant difference in vaccine efficacy between days 11 to 35 and 7 days after the second vaccine was administered.

Results raise more questions about the vaccine

Previous studies have found that the Pfizer-BioNTech vaccine increased immunoglobulin binding to S1 domain at days 21 and day 28 after vaccination. As the study found a lack of effect in the second dose of vaccine, it raises questions about the basic protective mechanism of both vaccines.

For example, mRNA vaccines can be strong promoters of innate immunity. SARS-CoV-2-secreted IgA is recommended as an important adjunct to natural infection. Antibody-activating actions can also enhance immunity. A better understanding of multifunctional protective devices as well as serum antibody binding or serum neutralizing antibody may be important for making good use of vaccine records, assessing the potential impact of changes new antigenic and developing new generation COVID-19 vaccines, ”the researchers wrote.

The team’s reanalysis also looked at long-term immunity up to day 111, but only after the second dose was administered. If a single vaccine can be fully immunized, the researchers question how long the immunity of the vaccine lasts.

Long-term protection from a single picture may help spread the vaccine and help people who have difficulty finding or registering a second vaccine on a particular day.

With the number of global cases reaching more than 114.7 million and the number of global deaths exceeding 2.5 million, a single-dose vaccine could help expand access to immunization-induced immunization SARS-CoV-2.

* Important message

medRxiv publish preliminary scientific reports that are not peer-reviewed and, therefore, should not be seen as final, guiding health-related clinical practice / behavior, or be treated as information established.