Review of pre-Omicron data finds COVID-19 vaccine protection from severe disease remains strong at six months

Date:
February 22, 2022
Source:
Johns Hopkins University Bloomberg School of Public Health
Summary:
A review of pre-Omicron evaluations examining four COVID-19 vaccines
finds protection against severe COVID-19 fell by 10 percent on
average from one to six months after full vaccination.



FULL STORY ==========================================================================
An analysis of research literature published last year before the
omicron variant took hold found that while COVID-19 vaccines lose some effectiveness in preventing SARS-CoV-2 infection, the vaccines retain
nearly all of their ability to prevent severe disease up to six months
after full vaccination. The study, which appears online February 21 in
The Lancet, was led by researchers at the Johns Hopkins Bloomberg School
of Public Health and the World Health Organization.


==========================================================================
For their study, the researchers analyzed vaccination effectiveness data published last year from June 17 to December 2 in both peer-reviewed
journals and on preprint servers, which post papers ahead of peer
review. The data - - detailed in 24 papers -- covered dozens of individual vaccine evaluations preceding the emergence of the currently dominant
omicron variant.

The researchers found that the level of protection from SARS-CoV-2
infection fell by about 21 percentage points, on average, in the interval
from one to six months after full vaccination -- whereas the level of protection against severe COVID-19 fell by only about 10 percentage
points in the same interval. The authors defined "full vaccination"
as one dose of Janssen vaccine or two doses of other vaccines. Booster
doses were not evaluated.

"There is an indication here of waning vaccine effectiveness over time,
though it is encouraging that protection from severe disease -- the
most worrisome outcome -- seems to hold up well," says study co-first
author Melissa Higdon, MPH, a research associate in the Department of International Health and a member of the International Vaccine Access
Center (IVAC) at the Bloomberg School.

How long vaccines protect from infection and severe disease is one
of the most urgent questions facing public health professionals and policymakers in the COVID-19 pandemic. To address the question, the
researchers identified 24 studies, published in journals or posted
on preprint servers June 17 to December 2 last year and covering the
four major Western-developed vaccines - - Pfizer, Moderna, J&J, and AstraZeneca. Many papers contained multiple vaccine evaluations. The researchers combined the data from the different studies using statistical tools to estimate an average change in vaccine effectiveness over time.

The finding that protection dropped against detected infection by an
average of 21.0 percentage points over five months means that a vaccine providing 90 percent protection from infection at 1 month would provide
only 69 percent protection at 6 months. The average drop was essentially
no different among vaccinated persons older than 50 when analyses were restricted to just their data.



========================================================================== Similarly, protection against symptomatic illness from SARS-CoV-2
infection - - which includes both mild and severe illness -- dropped on
average by 24.9 percentage points among persons of all ages, and 32.0 percentage points among older persons, from one month to six months post-vaccination.

Public health officials often emphasize vaccination for its protection
against severe COVID-19. For this more serious outcome, vaccine protection apparently was more durable, with effectiveness dropping on average by
just 10 percentage points during the one- to six-month interval. The
slight drop was similar for older persons who are at increased risk for
severe COVID-19 outcomes.

An analysis of post-vaccination infections with only the delta variant
also found waning protection over time, suggesting that declining immunity
-- rather than changes in protection against the delta variant -- was
the principal reason for the waning vaccine effectiveness prior to the
omicron wave.

The study is broadly consistent with others that have looked at vaccine effectiveness over time, and suggests that the four vaccines on average,
during pre-omicron waves, have provided good protection against the
severe outcomes that are most relevant to public health concerns.

"Omicron is still prevalent in many parts of the world, so it's going to
be critical for COVID-19-related policymakers to pay attention to vaccine effectiveness studies in the context of omicron as well as any future
variants -- and to assess effectiveness over extended periods of time
after vaccination, including vaccination with booster doses," Higdon says.

Higdon is a member of a research team led by study co-senior author Maria Deloria Knoll, PhD, senior scientist in the Bloomberg School's Department
of International Health and director of epidemiology at IVAC. The other co-first and co-senior authors were, respectively, Daniel Feikin MD,
and Minal Patel MD, of the Department of Immunizations, Vaccines, and Biologicals at the World Health Organization.

"Duration of effectiveness of vaccines against SARS-CoV-2 infection and
COVID- 19 disease: Results of a systematic review and meta-regression"
was co-authored by Daniel Feikin, Melissa Higdon, Laith Abu-Raddad, Nick Andrews, Rafael Araos, Yair Goldberg, Michelle Groome, Amit Huppert,
Katherine O'Brien, Peter Smith, Annelies Wilder-Smith, Scott Zeger,
Maria Deloria Knoll, Minal Patel.

The study was supported by the Coalition for Epidemic Preparedness
Innovations.

========================================================================== Story Source: Materials provided by Johns_Hopkins_University_Bloomberg_School_of_Public Health. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Daniel R Feikin, Melissa M Higdon, Laith J Abu-Raddad, Nick Andrews,
Rafael Araos, Yair Goldberg, Michelle J Groome, Amit Huppert,
Katherine L O'Brien, Peter G Smith, Annelies Wilder-Smith, Scott
Zeger, Maria Deloria Knoll, Minal K Patel. Duration of effectiveness
of vaccines against SARS- CoV-2 infection and COVID-19 disease:
results of a systematic review and meta-regression. The Lancet,
Feb. 21, 2022; DOI: 10.1016/S0140-6736 (22)00152-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220222121237.htm

--- up 11 weeks, 3 days, 7 hours, 14 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)