Moderna would be more effective than Pfizer against the Delta variant. While both sera protect against Covid-19, two independent studies have shown that US serum is more effective against the predominant variant , known as Delta or Indian , than Pfizer BioNTech’s vaccine.
The first study, published in medRxiv analyzed over 50,000 patients from the Mayo Clinic and found that serum Modern has an effectiveness of 76% against Delta variant, while that of Pfizer was 42% . Thus, the efficacy of both vaccines against Delta, compared to the original variant, fell just 10 points in the case of Moderna and 34 points in the case of Pfizer.
Although both vaccines are safe and protect against Covid-19, experts are considering the option of inoculating a third booster dose of Moderna to people who have already received the full regimen of this, or the Pfizer vaccine. This decision would be in favor of ensuring correct immunity, said the study’s lead author, Dr. Venky Soundararajan.
Another independent study offers the same conclusions. In this study, 199 elderly from nursing homes in Ontario, United States were analyzed. The antibody immune response was notably stronger after receiving Moderna’s serum than Pfizer’s. However, the study recommends monitoring the immune response and does not rule out the possibility of a booster dose in the vulnerable population.
THE EFFECTIVENESS OF PFIZER DECREASES OVER TIME
On the other hand, a follow-up of more than 34,000 Israelis found that Pfizer’s effectiveness against the virus that causes Covid-19 would decrease over time . From five months onwards, the chances of testing positive for coronavirus are considerably higher than after less than five months of receiving the full regimen.
Of this total of people, around 1.8% tested positive and the hypotheses of being infected with the virus were higher when at least 146 days had passed since the second dose and the person was older than 60 years.
However, study co-author Dr. Eugene Merzon of Israel’s Leumit Health Services adds that of these positive people “very few required hospitalization and it is too early to assess the severity of these new infections in terms of hospital admission, need of mechanical ventilation or mortality ”. He adds that he is «considering continuing with the investigation.»
Israel, which was one of the first countries to begin mass vaccinating the population, has already begun to strengthen the immunity of those over 60 and immunosuppressed patients with third doses.