As long as there have been vaccines against COVID-19, there has been an argument as to why people should not get those vaccines. One of the more frequent and hairy arguments is that people who have already been infected with the pandemic coronavirus, SARS-CoV-2, do not need the vaccine. An infection will generate an immune response triggered by vaccines, the thinking goes. So, why dose the coveted vaccine wasted on people who already have an immune response against the virus—which could put those people at risk of vaccine side effects, though rare?
This is a valid question, and there is legitimate scientific debate about it. There are differing perspectives on the issue in the context of public health policy as well. For example, in Israel, people who have recovered from COVID-19 after testing positive in a PCR test may receive the vaccination.”green passIt is valid for up to six months. The pass allows them to enter different places just as it does for people who have been fully vaccinated. In the European Union, some member states offer similar We do “Digital COVID Certificate“For those who have recovered from COVID-19” And Only one dose of a two-dose mRNA vaccine was received.
In the US, however, public health officials are unclear in their approach: people are classified as vaccinated or unvaccinated, regardless of prior infection. It is an approach with many strengths, including strong scientific data supporting vaccination for people who are healthy. That data – which we will get into below – has consistently shown that the immune response to natural infections is extremely variable, thus unreliable. Vaccines, on the other hand, have repeatedly been proven to produce a highly protective immune response.
Vaccines are also remarkably safe, with some serious side effects occurring only very rarely. One of the most commonly associated 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 only approximate. 41 in a million, and cases are generally mild.
Compare this to actual COVID-19 infections – which can cause severe illness even in young, healthy people and cause persistent, months-long symptoms in up to half of those infected – there is no competition. Vaccines are safer. And they are equally safe for those who have been cured before. people with previous COVID-19 cases Vaccines are less likely to cause serious side effects They may have more side effects than people who haven’t been infected before, though.
The American approach also has logistical benefits. The simple categories of “vaccinated” and “uninfected” omit the messy and difficult step of finding out who has been infected and when. Since the early stages of the pandemic, the US has struggled – and is still struggling – to roll out accurate, widely available tests for SARS-CoV-2. Many people who have been infected have never officially tested positive. Others assumed they were infected when they may actually have had one of several other respiratory infections. And antibody tests that look for evidence of past infections are grossly inaccurate.
Although opponents argue that mass vaccination is driven by “rogue corporations” at all costs for singular profit, the fact remains that vaccines are extremely safe and provide strong, lasting protection against a virus to recovered people. has already killed more than 700,000 Americans.
efficacy and variability
This is not to say that the US approach does not have weaknesses. For one thing, the outlook can make vaccines worse. In many instances, vaccine effectiveness is estimated by comparing rates of COVID-19 cases between vaccinated and unvaccinated people. But in the US, unvaccinated people include people who have no immunity. And Recovered people, who have some immunity and thus, are expected to have fewer infections. This reduces case rates in the uninfected group and reduces estimates of vaccine efficacy.
Nevertheless, the efficacy estimates of vaccines are exceptionally good. A recent study found that Pfizer-BioNtech mRNA was stable with the vaccine 90 percent efficacy Against COVID-19 hospitalization for at least six months. A separate study found that the Moderna mRNA vaccine was 93 percent effective Against hospitalization among people without compromising immunity. Johnson & Johnson’s vaccine was 71 percent effective.
And again, many vaccine efficacy numbers are not attributable to past infection and may be artificially low because of this. how much less It is unclear. Since the start of the pandemic, researchers have repeatedly noted that the immune responses triggered by SARS-CoV-2 infections have varied wildly, with some weak responses seen in people with mild disease and strong responses in those with severe disease. There are.
In June last year, Ars reported in a study that researchers looking at SARS-CoV-2 antibodies in cured people found that the difference between the highest and lowest levels varied by a factor of more than 1,000. The researchers saw even greater variability when they looked at neutralizing antibodies—which are known to bind to viruses and prevent them from infecting cells. Neutralizing antibody levels exceeded the 40,000-fold threshold in people who recovered, and up to 20 percent of people had no detectable level of neutralizing antibodies.
Of course, antibodies are not the complete immune response that determines whether or not a person will be infected and, if they do, how severe their infection will become. However, antibodies can provide a fair gauge of how well a person is protected. A study that tracked 12,500 healthcare workers late last year 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 neutralizing antibody levels and vaccine safety.
A fundamental difference between vaccines and the immune responses triggered by natural infections is their specificity. In a natural infection, the entire SARS-CoV-2 virus infects cells in the respiratory tract. Responding immune cells can target any aspect of the virus as a whole. This creates a relatively large variety of antibodies that bind to different bits of SARS-CoV-2. Vaccines, meanwhile, only work up to key snippets of the immune system of SARS-CoV-2 – the virus’s spike protein. This is the protein that SARS-CoV-2 uses to enter human cells, and it is a major target of neutralizing antibodies. All antibodies in vaccines will target the spike protein. Although vaccines have lower antibody diversity than those previously infected, they do have higher levels of highly targeted antibodies. Think of it as the difference between hunting down a small virus with a shotgun and a sniper rifle.
With variable immune responses following infection come variable real-world data on how well a previous infection protects against re-infection, which has led to various public policy approaches. In A study conducted at the Cleveland Clinic and posted online in June, the researchers found that among 52,238 employees, there was no difference in COVID-19 case rates between employees who were pre-infected but were already infected, vaccinated and previously infected, and those without People with an infection were vaccinated. “Individuals who have had SARS-CoV-2 infection are unlikely to benefit from COVID-19 vaccination,” the authors concluded.
Still, 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 again in May and June. tested positive again during 2021. CDC researchers find that people Those already infected but uninfected were 2.34 times more likely to be re-infected compared to those who were previously infected and fully vaccinated.
The time frame for the CDC study coincides with the rise of the delta coronavirus variant in the US, which may also play a role in protection levels from past infections. In A French study published in July in NatureIn this study, researchers examined antibodies in 56 unvaccinated people who had recovered from SARS-CoV-2 infection before the rise of Delta. Six months after their infection and between the rise of Delta, the researchers found that their neutralizing antibody levels were 4 to 6 times lower in Delta compared to the earlier variants.
The researchers then looked at a separate group of 42 people who had gone through a year after SARS-CoV-2 infection. Of them 42, 26 were still illiterate and 21 had received a single dose of the vaccine. At that time, 26 without vaccination had extremely low levels of neutralizing antibodies against any SARS-CoV-2 variant, especially Delta. Many people had no detectable level of neutralizing antibodies against Delta. Meanwhile, the vaccinated group had high levels of neutralizing antibodies, similar to or above those who were fully vaccinated.
This finding has appeared in several studies. For example, a March study by researchers in Washington state found that a single dose of mRNA vaccine in cured people Enhanced levels of neutralizing antibodies against all SARS-CoV-2 variants by up to a thousand fold. and many more further studies have found that the vaccine dose causes skyrocketing antibody levels after infection. some data also suggested that the level of antibodies in recovered vaccines is even higher than in those who have only been vaccinated.
Overall, variable immune response to infection, low neutrality against Delta, and a clear increase in protection from a very safe, highly effective vaccine…