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How To Determine If A Vaccine Is Effective

Scientists all over the world have been working tirelessly to develop a vaccine that will prevent COVID-19, and now there is real hope that an effective vaccine could be approved in the near future. As the world waits in anticipation, trials are underway to test potential vaccines, and Pfizer and Moderna have both created vaccines that are looking promising so far. However, there is still more to be done before a vaccine will be approved for public use. So, how do the experts determine whether a vaccine works well? Let’s examine some of the science behind vaccine trials.

In most cases, a group of people who have received the vaccine is compared to a placebo group — that is, a group of people who haven’t received the vaccine. The placebo group acts as an important control factor, allowing scientists to compare the rates of infection between the two groups to determine if the vaccine is successful.

Vaccine Efficacy

Vaccine efficacy can be calculated in a few different ways and is stated as a percentage. The ultimate goal would be a vaccine efficacy of 100%, which would mean that the vaccine would work perfectly, completely eliminating the risk of infection. A vaccine rate of 50%, on the other hand, means that the risk of infection has been reduced by 50%, in other words, that people who have received the vaccine are 50% less likely to become infected than those who haven’t received it. Another way of looking at a 50% efficacy rate is that if a person who received this vaccine was exposed to the amount of the virus that would get an unvaccinated person sick, there would be a 50% chance that they would become infected.

Some vaccines may be very effective at preventing severe disease but not as effective at preventing mild or moderate illness or preventing infection entirely. The ideal result of the COVID-19 vaccine trials would be to measure the efficacy of vaccines to prevent any level of infection or disease. This would ensure that any vaccine that is eventually made available for public consumption is as effective as possible. However, this could be challenging because COVID-19 is sometimes asymptomatic, meaning that patients could be infected by the virus but not show any signs of illness. Creating a virus for a respiratory illness that effectively prevents asymptomatic cases of disease as well as mild, moderate, and severe symptomatic cases can be very challenging. So far, data from animals shows that those who are vaccinated may still be infected with asymptomatic cases of the disease.

Other Measures Of Effectiveness

However, the methods for measuring vaccine efficacy don’t end there. Another important factor is whether people who are vaccinated can spread illness to others. This can happen in cases where individuals are infected but asymptomatic. Viral shedding is when a virus replicates itself and is released into the environment. Using a vaccine to decrease viral shedding is one way that the spread of infection can be prevented. 

Vaccine effectiveness is one final method of measurement that is actually different from vaccine efficacy. While efficacy is measured in a laboratory within a controlled experiment that has ideal conditions, effectiveness is a measurement of how well the vaccine will work when it is used in the real world under less-than-ideal circumstances.

The good news? Vaccine trials are well underway and there are some promising results so far. For example, the Pfizer vaccine has efficacy rates of 90%, which is getting a lot of people excited. However, the public will have to be patient a little longer while scientists continue to test vaccines to ensure that they are safe to use and as effective as possible. 

In the meantime, it is important to continue practicing other methods of prevention such as frequent hand washing and social distancing. The COVID Pre-Check App is another important tool that will keep everyone safe while we wait for a vaccine. Individuals can perform self-assessment tests as well as receive results from medical tests and confirmation from a physician when they are safe to return to work. While there is no vaccine available yet, the COVID Pre-Check App helps to create safe work environments and prevent the spread of COVID-19, making both employers and employees feel comfortable and confident.