COVID-19 Vaccine: Second dose provides optimal protection to individuals infected between doses, study suggests

Date:
October 4, 2021
Source:
Bar-Ilan University
Summary:
A second dose of the COVID-19 vaccine should be offered to
individuals infected with the virus shortly after receiving the
first dose, a new study suggests.



FULL STORY ==========================================================================
A second dose of the COVID-19 vaccine should be offered to individuals
infected with the virus shortly after receiving the first dose, according
to findings recently published by the Azrieli Faculty of Medicine of
Bar-Ilan University and Ziv Medical Center.


==========================================================================
The study, published in the journal Epidemiology & Infection, tracked
a cohort of 541 Ziv Medical Center health care workers -- some of whom
had already recovered from COVID-19 -- to determine how those previously infected with COVID-19 responded to vaccination compared to those who
weren't infected.

In this joint study, health care workers at Ziv Medical Center, one of
the main hospitals in northern Israel, regularly provided blood samples
to measure their antibody levels following vaccination. A number of
differences emerged following sample analysis of individuals infected pre-
and post-vaccination, and those who were never infected.

Previously infected individuals who received one dose of the vaccine had
much higher IgG antibody levels than fully vaccinated workers who were
never infected. However, infection after the first dose (and before the
second) did not increase IgG levels, and individuals infected after the
first dose who never received the second had similar antibody levels
to those who received one dose and were never infected. Individuals in
the cohort infected post- vaccination had IgG antibody levels at 21 and
50 days similar to those never infected who received the same number of
doses and much lower than those infected pre-vaccination.

"Our study suggests that two doses of vaccine are needed in those who were infected shortly after the first dose," says epidemiologist Prof. Michael Edelstein, of Bar-Ilan University's Azrieli Faculty of Medicine. "Although
it was conducted on a small cohort, our data suggest that a second dose provides optimal protection to those patients infected between doses,"
he adds.

Edelstein collaborated with Dr. Kamal Abu-Jabal, of Ziv Medical Center
and the Azrieli Faculty of Medicine, and a team of colleagues from the
hospital and the medical school.

The researchers stress that larger studies should confirm or refute
the need for a second dose of COVID-19 vaccine in these individuals,
in particular in the context of emerging variants against which vaccines
are less effective.

The current findings build upon research published in February 2021 in
the journal Eurosurveillance. In that study, on the same cohort of health
care workers, the researchers reported evidence that those previously
infected with the virus responded very strongly to one dose of the Pfizer vaccine, regardless of when they were infected and whether or not they
had detectable antibodies against COVID-19 prior to receiving the vaccine.

Prof. Edelstein and colleagues are continuing to follow the cohort's
antibody response and immune system response, as well as the response
to the third dose for those who receive it.

========================================================================== Story Source: Materials provided by Bar-Ilan_University. Note: Content
may be edited for style and length.


========================================================================== Journal References:
1. Kamal Abu Jabal, Hila Ben-Amram, Karine Beiruti, Ira Brimat,
Ashraf Abu
Saada, Younes Bathish, Christian Sussan, Salman Zarka, Michael
Edelstein.

SARS-CoV-2 Immunogenicity in individuals infected before and after
COVID- 19 vaccination: Israel, January-March 2021. Epidemiology
and Infection, 2021; 1 DOI: 10.1017/S0950268821001928
2. Kamal Abu Jabal, Hila Ben-Amram, Karine Beiruti, Yunis Batheesh,
Christian Sussan, Salman Zarka, Michael Edelstein. Impact of
age, ethnicity, sex and prior infection status on immunogenicity
following a single dose of the BNT162b2 mRNA COVID-19 vaccine:
real-world evidence from healthcare workers, Israel, December 2020
to January 2021.

Eurosurveillance, 2021; 26 (6) DOI: 10.2807/1560-
7917.ES.2021.26.6.2100096 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211004104120.htm

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