#16,675
Last week the U.S. CDC and FDA Approved a 2nd Booster For Older Americans who are more than 4 months out from their 3rd shot, but there remain a lot of questions over the increased level of protection it may supply, and how long it might last.
On Tuesday, we looked at a Danish study that found a respectable (but waning) level of protection (66.2% to 77.3%) against severe disease > 120 days following the 3rd shot (1st booster). Researchers cited `relatively poor' protection against (asymptomatic or symptomatic) Omicron infection.
We don't have good data on the level of protection afforded by the 1st booter after 6 months, but it presumably continues to decline. All of which presents a quandary - particularly for those who live in regions (like the United States) - where COVID rates are currently low.
Should they get the booster now, and risk it losing effectiveness before the next wave hits, or should they wait for signs of an uptick?
Admittedly, there is probably no `one-size-fits-all' answer. But this week we do have the benefit of a new NEJM study out of Israel with preliminary data on the effectiveness and duration of a 4th booster.
While the news is generally positive (increased protection against severe illness), the study only followed patients for 6 weeks following their booster, leaving open the question of how long protection from a 4th booster lasts.
First a link and excerpt from the study (which you'll want to read in its entirety), followed by an NEJM podcast on the study.
Protection by a Fourth Dose of BNT162b2 against Omicron in Israel
Yinon M. Bar-On, M.Sc., Yair Goldberg, Ph.D., Micha Mandel, Ph.D., Omri Bodenheimer, M.Sc., Ofra Amir, Ph.D., Laurence Freedman, Ph.D., Sharon Alroy-Preis, M.D., Nachman Ash, M.D., Amit Huppert, Ph.D., and Ron Milo, Ph.D.
April 5, 2022
DOI: 10.1056/NEJMoa2201570
METHODS
Using the Israeli Ministry of Health database, we extracted data on 1,252,331 persons who were 60 years of age or older and eligible for the fourth dose during a period in which the B.1.1.529 (omicron) variant of SARS-CoV-2 was predominant (January 10 through March 2, 2022). We estimated the rate of confirmed infection and severe Covid-19 as a function of time starting at 8 days after receipt of a fourth dose (four-dose groups) as compared with that among persons who had received only three doses (three-dose group) and among persons who had received a fourth dose 3 to 7 days earlier (internal control group). For the estimation of rates, we used quasi-Poisson regression with adjustment for age, sex, demographic group, and calendar day.
(SNIP)CONCLUSIONS
Rates of confirmed SARS-CoV-2 infection and severe Covid-19 were lower after a fourth dose of BNT162b2 vaccine than after only three doses. Protection against confirmed infection appeared short-lived, whereas protection against severe illness did not wane during the study period.
Below you'll find a 20-minute podcast discussion on the above study. Highly recommended.
ECDC and EMA issue advice on fourth doses of mRNA COVID-19 vaccines
News story
6 Apr 2022
ECDC and EMA’s COVID-19 task force (ETF) have concluded that it is too early to consider using a fourth dose of mRNA COVID-19 vaccines (Pfizer’s Comirnaty and Moderna’s Spikevax) in the general population.
Both agencies agreed however that a fourth dose (or second booster) can be given to adults 80 years of age and above after reviewing data on the higher risk of severe COVID-19 in this age group and the protection provided by a fourth dose.
ECDC and EMA also noted that there is currently no clear evidence in the EU that vaccine protection against severe disease is waning substantially in adults with normal immune systems aged 60 to 79 years and thus no clear evidence to support the immediate use of a fourth dose. Authorities will continue to monitor data to determine if there is an increasing risk of severe illness among those who are vaccinated. If the current epidemiological situation changes and new signals emerge, it may become necessary to consider a fourth dose in this age group. In the meantime, national authorities will also consider local data in deciding whether to use a fourth dose in those people at higher risk.
For adults below 60 years of age with normal immune systems, there is currently no conclusive evidence that vaccine protection against severe disease is waning or that there is an added value of a fourth dose.
As re-vaccination campaigns could start in the autumn, authorities will consider the best timing for additional doses, possibly taking advantage of updated vaccines.
So far, no safety concerns have emerged from the studies on additional boosters.
Vaccination against COVID-19 remains the most effective way to prevent severe illness during the current pandemic, including severe illness caused by the Omicron variant.
ECDC and EMA urge EU citizens to complete their schedules for both initial and booster vaccinations in line with national recommendations. As of the end of March 2022, 83% of adults had received full initial vaccinations and only 64% had received a booster dose.
What the evidence says about second booster doses
Evidence on the effects of a fourth dose comes largely from Israel, where data indicate that a second booster given at least 4 months after first booster restores antibody levels without raising any new safety concerns. Data also suggest that a second booster provides additional protection against severe disease, although the duration of the benefits is not yet known and the evidence is still limited.
Details of the evidence assessed by both agencies is available in the joint ECDC-EMA statement on second boosters.
Other factors to be considered in vaccination campaigns
National authorities in the EU make final decisions on the roll-out of vaccines, including booster doses, taking into account factors such as the spread of infection, the effects of COVID-19 in different populations and the emergence of new variants.
ECDC and EMA will continue to review available evidence on the effectiveness of COVID-19 vaccines and update their recommendations accordingly. EMA will also consider all emerging data on the safety and effectiveness of booster doses with a view to updating the product information for COVID-19 vaccines where applicable.
Full statement
COVID-19: Joint statement from ECDC and EMA on the administration of a fourth dose of mRNA vaccines
While I expect I'll get the 4th COVID shot sometime in the months ahead, my own personal decision is to wait until we begin to see an uptick in cases here in the United States. Until then, I'll continue to wear a face mask in public indoor spaces, liberally use hand sanitizer, and hope for the best.
That said, anyone who hasn't gotten their first three shots would do well to get caught up now, while COVID activity is low.
While another large wave this summer or next fall may not be inevitable, the short history of COVID suggests it is more than likely.
