There have been many arguments against the use of vaccines to combat COVID-19 for as long as vaccines have existed. The most persistent argument is that people who have been infected by the pandemic coronavirus (SARS-CoV-2), don't require a vaccine. The idea is that an infection will produce immune responses similar to vaccines. Why waste vaccine doses on people with immune responses to the virus? This could also put them at risk for vaccine side effects.
This is a valid question and there is legitimate scientific discussion about it. Public health policy can also be influenced by different approaches. For example, in Israel, anyone who has recovered from COVID-19 and tested positive for PCR can receive a "Green Pass", a vaccine that lasts up to six months. This pass is valid for up to six months and allows them entry to many places, just like it does for fully vaccinated people. Some member states of the European Union offer a similar "Digital COVID Certificate", which is available to those who have recovered from COVID-19, and only received one dose of the two-dose mRNA vaccination regimen.
The US public health officials are clear in their approach. People are classified as either unvaccinated or vaccinated regardless of previous infection. This approach has many advantages, including strong scientific data that supports vaccination for those who have fully recovered. The data, which we will discuss below, has consistently shown that natural infections can cause unpredictable immune responses. Vaccines on the other hand have been repeatedly shown to produce highly protective immune responses.
The vaccines are extremely safe and have very few side effects. Myocarditis, which is an inflammation of the heart muscle, is one of the most serious side effects. However, even in this group, myocarditis is rare in males aged 12 to 29, and cases are usually mild.
This is a comparison with actual COVID-19 infection. These infections can cause severe illness even in healthy young people, and may leave patients suffering for months. Vaccines are safer. They are also safer for those who have already recovered. Even though people with COVID-19 past cases are less likely to experience serious side effects, they can still be affected by vaccines.
There are logistical advantages to the US approach. The simple categories of "vaccinated", "unvaccinated", and "vaccinated" eliminate the complicated and tedious task of determining who was infected. The US has struggled and continues to struggle to provide accurate, readily available testing for SARS-CoV-2 since the beginning of the pandemic. Many of those who were infected have never been officially confirmed positive. Some people assumed they were infected, when they could have had another respiratory infection. Antibody tests to look for past infections are often inaccurate.
Although some critics claim that mass vaccination is motivated by evil corporations that seek to make huge profits, vaccines offer strong and lasting protection against a virus that has already claimed the lives of more than 700,000.
Variability and efficacy
However, this doesn't mean that the US approach is perfect. The approach can make vaccines look terrible. Many cases of vaccine effectiveness are compared between unvaccinated and vaccinated individuals to determine the difference in COVID-19 rates. The unvaccinated in the US include those who have not been immunized and people who have recovered. They are expected to have fewer cases. This causes a drop in case rates and lowers vaccine effectiveness estimates.
Despite this, vaccines' effectiveness estimates are extremely high. Recent research found that the Pfizer BioNTech mRNA vaccination was stable with a 90 percent effectiveness against COVID-19 hospitalizations for at least six month. Another study showed that Moderna's mRNA vaccine was 93% effective against hospitalizations in people with no immunocompromising conditions. Johnson & Johnson's vaccine proved to be 71% effective.
Again, vaccine efficacy numbers may be artificially low because they don't take into account past infections. What is the exact amount? It is not clear. Researchers have observed that the immune response to SARS-CoV-2 infection has varied widely since the outbreak. Some of the weaker immune responses were seen in people with mild diseases, while others are stronger in those with severe disease.
Ars reported that researchers compared the levels of SARS-CoV-2 antibodies among people who had recovered from the virus in June last year. They found that there was a significant difference in the results between the highest and the lowest levels by over 1,000. Researchers also observed more variation when they examined neutralizing antibodies, which are known to bind the virus and stop it from infecting cells. The levels of neutralizing antibodies in the recovered individuals varied by a range of 40,000 to 20%.