No protective effect due to previous colds – healing practice

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Protective effect of antibodies against coronaviruses?

Do people develop so-called cross-reactive antibodies against coronaviruses from previous colds, which make them immune to COVID-19? Or are these antibodies at least able to prevent a severe course of the disease?

Whether so-called cross-reactive antibodies against endemic coronaviruses can also protect against COVID-19 was investigated in a recent study involving researchers from the University of Pennsylvania. The study was published in the English-language journal “Cell“Published.

Colds lead to antibodies against seasonal coronaviruses

People can actually develop special antibodies against seasonal coronaviruses from previous colds, which also cross-react with SARS-CoV-2. According to the researchers, such antibodies are only present in one in five people.

Antibodies could not prevent infection with SARS-CoV-2

In addition, most of these antibodies do not have a neutralizing effect, reports the research team. The antibodies are not able to prevent infections with SARS-CoV-2 and they also did not prevent severe COVID-19 courses, the scientists report. However, the research group found that SARS-CoV-2 infection improves antibodies against other coronaviruses, which could potentially contribute to cross-immunity.

Especially in winter, people often suffer from infections of the upper and lower respiratory tract, which are triggered by coronaviruses. There are some endemic human coronaviruses (hCoV), of which it was previously assumed that corresponding antibodies could also protect against SARS-CoV-2. These include, for example, the known human pathogenic coronaviruses HKU1 and OC43 and the alphacoronaviruses 229E and NL63. Like SARS-CoV-2, HKU1 and OC43 are counted among the so-called beta corona viruses, reports the team.

The researchers from the Perelman School of Medicine at the University of Pennsylvania analyzed serum samples from 431 people of different ages in the current study. The evaluated samples were created in 2017, i.e. before the COVID-19 pandemic. The experts then quantified the pre-pandemic antibody levels in the serum of a separate cohort of people in whom SARS-CoV-2 infection was confirmed using a PCR test. The research group wanted to find out whether infections with the viruses mentioned lead to at least a low level of protection against SARS-CoV-2 in the course of life.

The concentrations of antibodies against hCoV in the samples were evaluated by It was then tested whether these antibodies react to SARS-CoV-2 and it was also analyzed whether they could also protect against COVID-19 in such a case, the experts report.

It was found that most of the participants were already carrying hCoV-reactive antibodies before the COVID-19 pandemic. The researchers found that around 20 percent of these people had non-neutralizing antibodies that cross-reacted with SARS-CoV-2 spike and nucleocapsid proteins. However, these antibodies were not associated with protection against SARS-CoV-2 infections or fewer hospital stays, the team reports. However, the antibodies were significantly increased after a SARS-CoV-2 infection.

Weaker course of COVID-19 thanks to infections?

In a study in 2020, which was published in the English-language specialist journal “Journal of Clinical Investigation“Was published, there are indications that recent infections with endemic coronaviruses could contribute to stronger immune responses. These immune responses did not prevent SARS-CoV-2 infections, but severe disease courses of COVID-19 appeared to be rarer.

However, it remained unclear whether the apparently present cross-immunity is due to an antigen-specific cellular (T-cell response) or humoral (B-cell response). In addition, it is not yet known whether it is only a short-term cross-protection and whether past infections with the coronavirus lead to the production of antibodies that prevent SARS-CoV-2 infections or at least have an influence on the outcome of such an infection the researchers in the “Journal of Clinical Investigation”.

What role does age play in cross immunity?

Another question that arises, to which unfortunately there is no answer yet, is whether and what role the age of the sick person plays in cross-immunity. Since older people are more symptomatic and severely ill with COVID-19 than is the case with children, age does seem to have an influence.

Children and also younger adults could have a stronger pre-existing immunity against seasonal human coronaviruses, which cross-react with SARS-CoV-2, whereby a protective effect occurs against severe and even symptomatic SARS-CoV-2 infections, so the presumption. This is also indicated in an English-language journal “Science“Published study by researchers at Imperial College London. This showed that SARS-CoV-2 uninfected people can also carry antibodies that cross-react with the SARS-CoV-2 spike protein. A significantly higher proportion of children and adolescents have the corresponding antibodies compared to adults.

“This could be due to the fact that children and adolescents generally have higher hCoV infection rates and a more diverse antibody repertoire, which could explain the age distribution of COVID-19 susceptibility,” said the research team at Imperial College London. According to the researchers, the tests also showed a specific neutralizing activity of the antibodies against both SARS-CoV-2 and SARS-CoV-2 S pseudotypes.

Contradictory study results

The examples mentioned make it clear that there are certainly studies that assume a protective effect against SRAS-CoV-2 through previous infections with endemic coronaviruses. However, the research team from the University of Pennsylvania has now come to the conclusion that the antibodies do not protect against SARS-CoV-2 infections and also have no influence on the inpatient treatments required. Therefore, further investigations with much larger samples are urgently required in order to clear up the contradictions in the previous research results. (as)