At the end of July, there was a wave of panic and media revolt due to an “outbreak” of COVID-19 in the state of Massachusetts, where 469 people were infected and 74% of them (347) had been fully vaccinated. This was enough for the media to spread alarming headlines questioning, once again, the effectiveness of vaccines.
Recently, the state of Minnesota also reported an outbreak of 7,171 new cases, but only 0.24 % (17 cases) of those infected were fully vaccinated people. About 95 % of the new cases reported in Minnesota were of the Delta variant.
Once again, science debunks the myth. A study reviewed and approved by Mayo Clinic’s Institutional Review Board, published by the British Medical Journal and Yale University, indicated that messenger RNA vaccines manufactured by Moderna and Pfizer/BioNTech remain highly effective in preventing symptomatic COVID-19 infection, especially in preventing cases of hospitalization and death from the virus.
According to study data, Moderna’s vaccine was even more effective than Pfizer’s on all measures, although the difference is not large.
Moderna’s vaccine was between 76 % and 95 % effective in preventing infection and between 91.6 % and 95 % in avoiding hospitalization associated with the virus. Meanwhile, Pfizer’s was between 84 % and 95 % in preventing disease and is able to avoid hospitalization in 85 % to 97 % of cases.
On average, a person who has received both doses of either messenger RNA vaccine has 86% protection against infection.
The study also indicates that the vaccines prevent infection with the Delta variant to a lesser degree (Moderna 76% and Pfizer 42%), but even in those cases, the development of severe symptoms is unlikely and the likelihood of hospitalization is 1% to 6%.
Notably, the prevalence of the Delta variant in Minnesota increased from 0.7% in May to over 70% in July, while the prevalence of the Alpha variant decreased from 85% to 13% during the same time period. Something similar occurred in Iowa and Wisconsin. In Arizona, the Delta variant accounts for 100% of cases today, as it does in Florida.
However, the study still recommends follow-up results given the variation in effectiveness against infection. The study concludes, “While both COVID-19 mRNA vaccines strongly protect against infection and severe disease, further evaluation of the mechanisms underlying differences in effectiveness, such as dosing regimens and vaccine composition, is warranted.”
In other words, the study determines that the vaccines are effective and that after receiving the full vaccination, it is very unlikely to be hospitalized due to the development of severe symptoms. What is recommended is to continue studying the possibility of increasing the doses to ensure a higher rate of effectiveness in preventing infection.