No, your antibodies are no better than the vaccination: an explanation

As long as there have been vaccines against COVID-19, there have been arguments as to why people should not receive these vaccines. One of the most persistent – and hairiest – arguments is that people who have already been infected with the pandemic coronavirus, SARS-CoV-2, do not need a vaccine. An infection will generate immune responses similar to those generated by vaccines, according to the thought. So why waste coveted vaccine doses on people who already have immune responses to the virus, which can also put those people needlessly at risk for side effects from the vaccine, however rare they are?

This is a reasonable question, and there is a legitimate scientific debate about it. There are also different approaches to the issue in terms of public health policy. In Israel, for example, people who have recovered from COVID-19 after testing positive on a PCR test can get a “Green Pass” vaccine valid for up to six months. The pass allows them access to various places as it does for fully vaccinated people. In the European Union, some member states are offering a similar ‘COVID digital certificate’ to people who have recovered from COVID-19 and received a single dose of a two-dose mRNA vaccination schedule.

In the United States, however, public health officials are unequivocal in their approach: People are classified as vaccinated or unvaccinated, regardless of previous infection. It is an approach with many strengths, including strong scientific data supporting the vaccination of people who have recovered. These data – which we will discuss below – have always shown that the immune responses of natural infections are extremely variable, and therefore unreliable. Vaccines, on the other hand, have repeatedly proven to generate highly protective immune responses.

The vaccines are also remarkably safe, with few types of serious side effects that occur very rarely. One of the most concerning side effects is myocarditis (inflammation of the heart muscle). But even there, the rate of myocarditis in the highest risk group (men aged 12 to 29) is estimated at only 41 in a million, and cases are usually mild.

Comparing this with actual COVID-19 infections – which can cause serious illness even in young, healthy people and can cause symptoms that persist for months in up to half of those infected – there is no has no dispute. Vaccines are safer. And they’re just as safe for people who have already recovered. People who have had cases of COVID-19 are no more likely to have serious side effects from vaccines than people who have not been infected before, although they may have more side effects.

The American approach also has logistical advantages. The simple categories of “vaccinated” and “unvaccinated” skip the complicated and difficult step of determining who was infected and when. Since the early stages of the pandemic, the United States has struggled – and still struggles – to deploy accurate and widely available tests for SARS-CoV-2. Many infected people have never officially tested positive. Others assumed they were infected when they may have had one of the many other respiratory infections. And antibody tests that look for evidence of past infections are notoriously inaccurate.

Although opponents argue that mass immunization is carried out by “evil companies” in search of stupendous profits at all costs, the fact is that vaccines are extremely safe and provide people who are cured with strong and lasting protection against a virus. which has already killed over 700,000 Americans.

Efficiency and variability

This is not to say that there are no weaknesses in the United States’ approach. On the one hand, the approach can make vaccines look bad. In many cases, the vaccine’s effectiveness is assessed by comparing the rates of COVID-19 cases between vaccinated and unvaccinated people. But in the United States, the unvaccinated include people who have no immunity and people who are cured, who have some immunity and therefore should have fewer infections. This decreases the case rates in the unvaccinated group and ultimately lowers the estimates of vaccine effectiveness.

Yet the estimates of vaccine effectiveness are extraordinarily good. A recent study found that the Pfizer-BioNTech mRNA vaccine was maintained at 90% efficacy against COVID-19 hospitalization for at least six months. A separate study found that Moderna mRNA vaccine was 93% effective against hospitalizations in people without immunocompromised conditions. Johnson & Johnson’s vaccine was 71 percent effective.

And again, many vaccine effectiveness figures ignore past infections and may be artificially lower because of it. How much lower? It’s unclear. Since the onset of the pandemic, researchers have repeatedly noted that the immune responses generated by SARS-CoV-2 infections vary widely, with some of the weakest responses seen in people with mild illness and severe disease. stronger responses in people with severe illness.

In a study reported by Ars in June of last year, researchers examining anti-SARS-CoV-2 antibodies in people who had recovered found that the difference between the highest and lowest levels varied. by a factor of over 1,000. The researchers saw even more variability when they looked at neutralizing antibodies, those known to bind to the virus and prevent it from infecting cells. The levels of neutralizing antibodies in the recovered people varied over a range of 40,000 times, and up to 20% of the people had no detectable level of neutralizing antibodies.

Antibody

Of course, antibodies are not the entirety of the immune responses that determine whether or not a person will be infected and, if they do, the severity of their infection. However, antibodies can provide a reasonable indication of a person’s degree of protection. A study late last year that followed 12,500 healthcare workers found that the higher the antibody levels, the lower the risk of infection. And in May of this year, researchers found a “remarkably strong” relationship between levels of neutralizing antibodies and vaccine protection.

A fundamental difference between the immune responses generated by vaccines and natural infection is their specificity. In natural infection, whole SARS-CoV-2 viruses infect cells in the respiratory tract. Responding immune cells can target any number of facets of these entire viruses. This creates a relatively large diversity of antibodies that bind to different pieces of SARS-CoV-2. Vaccines, on the other hand, are only used for key extracts of the immune system of SARS-CoV-2, namely the spike protein of the virus. It is the protein that SARS-CoV-2 uses to enter human cells, and it is a key target for neutralizing antibodies. All antibodies in the vaccinee will target the spike protein. Although vaccinees have less antibody diversity than previously infected people, they have high levels of highly targeted antibodies. Think of it as the difference between hunting a little virus with a shotgun and a sniper rifle.

With varying immune responses after infection, varying real-world data on how past infection protects against reinfection, which has led to different public policy approaches. In a study conducted at the Cleveland Clinic and published online in June, researchers found that among 52,238 employees, there was no difference in the rates of COVID-19 cases between unvaccinated but previously infected employees. , vaccinated and previously infected, and people vaccinated unprecedented. infection. “People who have had an infection with SARS-CoV-2 are unlikely to benefit from the COVID-19 vaccination,” the authors concluded.

Yet in another study published in August by the Centers for Disease Control and Prevention, researchers looked at the vaccination status of more than 200 Kentucky residents who tested positive for SARS-CoV-2 in 2020 and then again. tested positive in May and June. 2021. CDC researchers found that people previously infected but not vaccinated were 2.34 times more likely to be re-infected than people previously infected and fully vaccinated.

Delta difference

The CDC’s study timeline coincides with the increase in the delta coronavirus variant in the United States, which may also play a role in levels of protection against past infections. In a French study published in July in Nature, researchers looked for antibodies in 56 unvaccinated people who had recovered from SARS-CoV-2 infection before the delta surged. Six months after their infection and in the midst of the increase in delta, the researchers found that their neutralizing antibody levels were 4 to 6 times lower against delta than they were against previous variants.

The researchers then looked at a different group of 42 people who had passed a year since being infected with SARS-CoV-2. Of these 42 people, 26 were still not vaccinated and 21 had received a dose of the vaccine. At this point, the 26 unvaccinated had extremely low levels of neutralizing antibodies against all variants of SARS-CoV-2, especially delta. Many people did not have detectable levels of neutralizing antibodies against delta. The vaccinated group, on the other hand, had elevated levels of neutralizing antibodies similar to or higher than levels seen in people who were fully vaccinated.

This conclusion has played out in several studies. A March study by researchers in Washington state, for example, found that a dose of an mRNA vaccine in people who had recovered increased levels of neutralizing antibodies against all variants of SARS- CoV-2 up to a thousand times. And several other studies have shown that doses of vaccine after infection cause dizzying spikes in antibody levels. Some data has also suggested that antibody levels in retrieved vaccines are even higher than in people who have only been vaccinated.

Overall, the varying immune responses to infection, the weaker neutralization against delta, and the marked increase in protection from a very safe and highly effective vaccine is a strong argument in favor of vaccinating the cured.