Vaccine protection against SARS-CoV-2 infection wanes quickly but is
better maintained against severe disease, study finds

Date:
February 7, 2022
Source:
Umea University
Summary:
The vaccine-induced protection against SARS-CoV-2 infection wanes
within a couple of months, but at different speed according to
vaccine type.

However, protection against severe COVID-19 appears to be better
maintained, according to a study by researchers in Sweden.



FULL STORY ==========================================================================
The vaccine-induced protection against SARS-CoV-2 infection wanes
within a couple of months, but at different speed according to vaccine
type. However, protection against severe COVID-19 appears to be better maintained. This is shown in a nationwide, registry-based study performed
by researchers at Umeaa University, Sweden, that now is published in
The Lancet.


==========================================================================
"The bad news is that the protection against infection seems to
be diminished by seven months after the second dose of vaccine,"
says Peter Nordstro"m, professor of geriatric medicine at Umeaa
University. "The good news, however, is that the protection against
a severe infection that leads to hospitalization or death seems to be
better maintained. Vaccination is therefore very wise and important."
The study, which received much attention once first posted as a 'preprint'
in October, has now been peer-reviewed and the results as such confirmed.

Following extensive revision and additional analyses, leading to results
that more clearly show that the protection against severe COVID-19 seems
better maintained than that against infection, the study has now been
published in The Lancet.

The study is a nationwide, observational study based on registry-data
from the Public Health Agency of Sweden, the National Board of Health
and Welfare, and Statistics Sweden. The main analysis included almost
1.7 million individuals, and the results were confirmed in an even
larger population of almost 4 million individuals. The results showed
that protection against infection of any severity waned progressively
following the peak which occurred a month after the second dose.

Six months after vaccination, the remaining protection against infection
was 29 per cent from two doses of Pfizer, and 59 per cent from two doses
of Moderna.

There was no remaining protection from months and onwards for
AstraZeneca. With respect to infections that were severe enough to warrant
a hospital stay, or where the individual died within 30 days of confirmed infection, the protection was better maintained.

Protection against severe disease was 89 per cent after one month and
64 per cent from four months an onwards during the rest of the maximum follow-up of nine months. There was some evidence to suggest a lower
protection in the oldest individuals and in individuals with homemaker
service.

"The results underscore and support the decision to offer a third dose,"
says Marcel Ballin, doctoral student in geriatric medicine at Umeaa
University and co-author of the study. In particular, the results show
that it was correct to prioritize the oldest and frailest individuals."
Prior to this study, a few observational studies and follow-up studies
of the clinical trials have investigated waning vaccine protection in
other countries.

However, these have mostly covered the initial four to six months,
and for the Pfizer vaccine.

"What this study contributes with is the longer follow-up time and the
fact that we were able to explore how well the protection is maintained according to different types of vaccines," says Anna Nordstro"m, adjunct professor in public health at Umeaa University and co-author of the study.

"The strengths are that we have been able to do this in a real-world
setting based on a population-based sample of the total population
of Sweden. This increases the possibility to generalize the results
to other countries with similar population structure as in Sweden." ========================================================================== Story Source: Materials provided by Umea_University. Original written
by Ola Nilsson. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Peter Nordstro"m, Marcel Ballin, Anna Nordstro"m. Risk of infection,
hospitalisation, and death up to 9 months after a second dose of
COVID-19 vaccine: a retrospective, total population cohort study
in Sweden. The Lancet, 2022; DOI: 10.1016/S0140-6736(22)00089-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220207100117.htm

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