Booster doses of mRNA vaccines protected against severe COVID-19 from Omicron
Booster doses of mRNA vaccines protected against severe COVID-19 from Omicron

Booster doses of mRNA vaccines protected against severe COVID-19 from Omicron

Booster doses of mRNA COVID-19 vaccines provided strong protection against hospitalization and death during the Omicron wave of the Qatar pandemic, despite being less effective against symptomatic infection, a new study confirmed.

The study, published in New England Journal of Medicine, analyzed data from 2,239,193 people in Qatar who had received at least 2 doses of either the Pfizer-BioNTech or Moderna COVID-19 vaccines. In two matched retrospective cohort studies, investigators assessed the efficacy of the vaccines during the Omicron increase from December 19 to January 26 among those who received boosters compared to those who received only the primary two-dose series.

“There are significant benefits to having a booster as it reduces the likelihood of getting a symptomatic Omicron infection by about 50%,” said study author Laith Jamal Abu-Raddad, Ph.D. Infection. “The efficiency of the booster against COVID-19 hospitalization and death is even better by about 80%. Having a booster recently is very protective against COVID-19 hospitalization and death due to Omicron.”

The primary outcomes were symptomatic infection and secondary outcomes were severe, critical or fatal cases of COVID-19.

Among those receiving the Pfizer BioNTech vaccine, the incidence of symptomatic infection from the Omicron variant was 2.4% among those receiving a booster and 4.5% among those receiving only the primary series. The estimated efficacy of the booster against symptomatic disease from the Omicron variant was 49.4%. The efficacy of the Pfizer-BioNTech vaccine against severe, critical or fatal COVID-19 was 76.5%. The efficacy of the Pfizer BioNTech vaccine against the Delta variant was 86.1.

Among those receiving the Moderna vaccine, the incidence of symptomatic infection from the Omicron variant was 1% among those receiving a booster and 1.9% among those receiving only the primary series. The estimated efficacy of the booster against symptomatic disease from the Omicron variant was 47.3%. No serious, critical, or fatal COVID-19 cases were reported among those receiving Moderna booster, and three serious cases were reported among those receiving only the primary series.

“The fact that the protection is only 50% against Omicron is not the best,” Abu-Raddad said. “Compared to previous variants like Delta, we had much better protection, more than 80%. This suggests that we need to start thinking about developing a new generation of vaccines with high protection against a wide range of variants and an efficiency, which does not decrease rapidly. “

To check for declining immunity, the study matched pairs of people exactly according to the calendar week they received their second dose of an mRNA vaccine.

“As long as we have the current generation of vaccines, newer booster vaccinations are essential to protect those most vulnerable to COVID-19 hospitalization and death,” Abu-Raddad said.

Abu-Raddad said investigators will continue their research with lengthy follow-up of the vaccinated cohorts to see how the effectiveness of the booster shot will decrease over time.

Recent studies have shown that the efficacy of COVID-19 mRNA vaccines decreases over time. US Centers for Disease Control and Prevention reported that protection against hospitalization during the Omicron wave dropped from 91% two months after an mRNA booster to 78% after four months.

ONE recent study found that decreasing protection after full vaccination was more significant for the efficacy of the vaccine than the emergency of the Delta variant.

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