All vaccines do the right thing

Vaccines against the virus that causes COVID-19 work, but are all vaccines the same? The most important effect of vaccines is to prevent a person from becoming seriously ill or dying from an infection. Currently, available vaccines do this. However, another important effect of a vaccine is to shut down the chance of more infectious variants, such as the Delta variant, from infecting more people and at a faster rate. There appear to be differences between mRNA vaccines (Pfizer and Moderna) and the ones made from genetically modified cold viruses (Johnson & Johnson and AstraZeneca). For example, mRNA vaccines teach our cells how to make a protein (or part of a protein) that creates an immune response. This immune response then produces antibodies, protecting us from getting infected if the virus enters our body. It is important to note that mRNA vaccines do not contain live COVID virus.

mRNA vaccines are very good at reducing the risk of passing on infection

New data from the United States and Qatar suggest that the mRNA vaccines are more effective at preventing new infections. The researchers compared more than 54,000 veterans testing positive for the COVID virus with an equal number who tested negative. They found that the Pfizer and Moderna vaccines were 96% to 98% effective in preventing infection. In the Qatar study, using a similar approach, two Moderna shots were 92.5% effective in preventing asymptomatic infection (infection without symptoms) with any variant circulating at the time. The shots were also 100% effective against any infection with the Alpha variant, and 96.4% effective against infection with the Beta variant. Elsewhere, a different U.S. study showed that these vaccines were 90% effective in preventing infection in frontline workers.

Other effective vaccines will soon become available

These studies were completed before the Delta variant appeared. However, the lab studies are promising, suggesting that mRNA vaccines may stop asymptomatic Delta infection, too. In comparison, the other vaccines appear to be less effective at preventing the spread of infection. The soon to be approved Novavax may be even more effective.

Any vaccine is better than no vaccine

However, as vaccine access is a challenge around the world, any vaccine is better than one which is unaffordable.


Photo by Spencer Davis on Unsplash