The Centers for Disease Control and Prevention (CDC) stated, earlier this week, that booster shots of the anti-COVID vaccines have indeed been able to significantly reduce the risk of immunocompromised people ending up hospitalized because of a severe infection with the virus.
More precisely, according to a study in the CDC’s Morbidity and Mortality Weekly Report, in the case of adults hospitalized after receiving the first two mRNA vaccine doses, it seems like the effectiveness of the vaccines was able to reach 88 percent!
On the other hand, the same two doses were only 69 percent effective in the case of immunocompromised people!
The research involved almost 3,000 adult patients admitted to 21 hospitals across 18 American states between August 19 and December 15 last year.
More precisely, there were 1,385 case patients and 1,567 non-COVID-19 control cases.
The CDC pointed out that the analysis started a week after the FDA (Food and Drug Administration) authorized an additional vaccine dose for emergency use specifically for those over the age of 12 and who suffer from immunocompromising conditions.
This extra dose can be received after at least 28 following their second shot.
The effectiveness of the vaccine was calculated for both sides by just comparing the chances of previous vaccination between COVID patients and the healthy control group.
The regression model was also adjusted for admission date, age groups, hospital region as well as self-reported ethnicity and race.
Other models were then generated for the immunocompetent patients as well as people with immunocompromising conditions, these analyses being conducted via Stata software.
While control patients received negative NAAT tests (nucleic acid amplification tests), those who had COVID-like illness got positive test results by a NAAT test or antigen test.
Furthermore, either patients or their proxies were interviewed about clinical and demographic characteristics but medical record searches were also conducted.
Proof of previous vaccine doses was also obtained through self-report and documentation.
There were three main groups considered, namely unvaccinated, two dose mRNA recipients and finally, those who had already received 3 doses of the vaccine.
The conclusion was that three doses of the Pfizer or Moderna vaccines were around 97 percent effective in preventing hospitalizations in people with stronger immunity as compared to those who had received two doses of the vaccine, who accounted for 82 percent effectiveness.
It has to be mentioned that this study was conducted back when the delta variant was still the dominant strain of the COVID-19 virus in the United States.
Naturally, you may know that now, the omicron variant makes for almost 100 percent of all new cases in the country.
As a result, there can still be some significant limitations to the aforementioned findings.
Other limitations stem from the fact that while the findings include that vaccinated patients from both dose groups were similar as far as clinical characteristics and demography are concerned, it’s possible they varied when it comes to other factors such as exposure risks.
Vaccine effectiveness against mild infection was also not assessed, the same being the case for the possibility of receiving a fourth dose for those who are immunocompromised.
Finally, the last significant limitation of this study consists in the fact that most of the subjects who had received 3 doses of the vaccine had been vaccinated only a few weeks before joining it, hence durability of protection could not be properly assessed.
This, in turn, means that further analysis focused on durability is required for more conclusive results.
The CDC wrote that “Early evidence suggests that a 3rd mRNA vaccine dose elicit markedly stronger neutralizing antibody response to omicron compared with responses to 2 vaccine doses, and increases [vaccine effectiveness] against more severe disease following an infection with the omicron variant. The effectiveness of receiving 3 doses of COVID-19 mRNA vaccines against a range of severity associated with the omicron variant needs to be evaluated carefully in different populations.”
Regulators said, earlier this month, that adults can now receive booster shots at least 5 months following their second dose.
As per the American Medical Association, there are currently around 7 million people with weakened immune systems all over the US.
With the spread of omicron, the White House has been encouraging American citizens to make sure to receive their booster shots.
The CDC also confirmed that a third dose of the vaccines plays a big role in protecting immunocompromised adults against severe forms of COVID-19 infection that would otherwise lead to hospitalization and many complications as well as a serious risk of death.
Data shows that among people with and without immunocompromising conditions determined to be eligible for a booster shot, a third dose increased protection way beyond what the baseline of two doses can do as far as avoiding hospitalizations is concerned.
