Effectiveness
In terms of numbers, it seems Moderna’s mRNA-1273 has a bit of an advantage because of its 94.5% effectiveness at preventing COVID-19. Of the 30 000 participants, 95 patients were diagnosed with COVID-19; 90 of them received a placebo while 5 received the coronavirus vaccine.
On the other hand, Pfizer and BioNtech’s BNT162b2 vaccine reportedly has “above 90%” effectiveness. The pharmaceutical companies did not give specific details regarding the 94 COVID patients involved in the trials, but simple math suggests there were 86 cases in the placebo group and 8 in the vaccine group, thus the slight rounding down to 90 percent.
In practical terms, 94.5% and “above 90%” is not such a big difference, considering the small number of cases the results were based on. One or two more people in the vaccine groups could tip the scale in anyone’s favor. Also, the way the clinical trials were organized could have also affected the effectiveness percentages. Pfizer and BioNTech started counting COVID-19 cases one week after patients received the second dose while Moderna started counting two weeks after the second dose.
Safety
In terms of safety, both pharmaceutical companies claimed there weren’t “any serious safety concerns” reported by the independent data monitoring board. Moderna, however, reported several side effects after the second dose, including fatigue in 9.7% of patients, muscle pain in 8.9% cases and joint pain in 5.2% of patients. Only 2.7 percent of patients in the study reported injection site reactions after they received the first dose.
Generally, the severe side effects from vaccines occur in the first two months after receiving the shot, which is why the Food and Drug Administration requires all companies developing vaccines to collect safety data from half of the patients involved in the trials before applying for authorization to distribute the vaccine.
