What we learned about COVID-19 reinfection

A Research Of the more than 20,000 healthcare workers in the UK, only 44 of the more than 6,600 previously infected with SARS-CoV-2 were found to be re-infected. Less than 1 percent.

In addition, those who had previously been infected were 83% less likely to be re-infected during the five months of the study than those who were not previously infected.

The results were published on the preprint server medRxiv on January 15th. This study has not been peer reviewed, so the results should be viewed carefully.

However, these results are Another study Performed by Dr. Stuart C. Sealfon, Professor of Neurology, Neuroscience, Pharmacology, and Colleagues at Mount Sinai School of Medicine.

The group tracked more than 3,000 Marines who participated in basic training in South Carolina. This includes approximately 190 recruits who were previously infected with SARS-CoV-2.

During the six weeks of the study, about 10% of previously infected people had another infection. However, it is 82% less likely to be infected than a recruit who has never been infected before.

“The risk of reinfection is about one-fifth that of the first infection,” says Sealfon. “Therefore, previous infections provide considerable protection, but reinfections are not uncommon.”

This study was published on January 29th at medRxiv. We are also waiting for peer reviews.

Since these studies have been conducted, new SARS-CoV-2 mutants have emerged that may at least somehow circumvent the immune protection gained when people successfully fight the virus.

“A few [SARS-CoV-2] Subspecies may increase the risk of reinfection more than we have seen [in our study]”Sealphone said.

Each time this coronavirus replicates (it replicates very quickly), mutations can occur. This applies to all viruses.

Scientists estimate The SARS-CoV-2 RNA genome acquires single-letter changes approximately twice each month. This is about half as fast as the flu virus.

Some mutations are harmful to the virus. These are eventually eliminated from the virus population or reduced to low levels. However, other mutations give the virus an advantage over our immune system.

Scientists are now on the lookout for three rapidly expanding things variant It was first identified in the United Kingdom (B.1.1.7 variant), South Africa (B.1.351 variant), and Brazil (P.1 variant).

Both B.1.1.7 variant And that B.1.351 variant It is believed to spread more easily and quickly. B.1.1.7 can also be the cause More serious illnessBut scientists are still investigating this.

Another concern is that certain mutations allow the mutant to evade the immune system, which can increase the likelihood of reinfection. Scientists are doing research to determine how likely this is.

In one Research Because not peer-reviewed, researchers collected serum samples from 44 people who recovered from COVID-19. These samples contained antibodies produced by the immune system to fight the coronavirus.

Researchers have serum samples from 21 of these participants It was not possible to neutralize the B.1.351 variant in the laboratory. The virus was also partially resistant to most of the remaining samples.

The results highlight the possibility of “reinfection with antigenically different mutants,” the authors report.

Cases of reinfection with new variants have also been recorded, including a man who had a second infection in Israel. B.1.351 variant, And those who have a second infection P.1 variant..

Similar to the men mentioned in the BMJ case report, Israeli men showed mild symptoms during reinfection. This suggests that even in the event of reinfection, there is sufficient immune protection to prevent more serious illness.

The ability of certain mutations to evade the immune system is related to the ability of the COVID-19 vaccine to protect not only those who have been infected with COVID-19, but also those who have never been infected.

The COVID-19 vaccine protects people by stimulating the immune system to fight SARS-CoV-2 infection without actually causing COVID-19.

The side effects experienced by vaccinated people are not symptoms of the disease. Rather, they are a sign that the immune system is learning to recognize and fight the coronavirus.

A laboratory study by Hatziioannou and her colleagues suggests that certain SARS-CoV-2 mutations in peplomers may circumvent the protection provided by the COVID-19 vaccine. I am.

SARS-CoV-2 uses spike proteins to infect cells in the body. Binding to the receptor On the surface of human cells called ACE2.

Hatziioannou Research, Researchers collected plasma from 20 people who received the Moderna-NIAID or Pfizer-BioNTech vaccine. They tested this against a pseudovirus containing a specific peplomer mutation found in the new SARS-CoV-2 mutant.

Antibodies from vaccinated people were less effective against pseudoviruses containing these mutations compared to pseudoviruses with the original peplomer composition.

This study was published on the preprint server bioRxiv. Hatziioannou said the treatise was approved for publication in Nature.

Vaccine makers have also tested vaccines in the laboratory to see how well they work against new variants, and the results are mixed.

Preliminary data It suggests that the Pfizer-BioNTech vaccine works against the B.1.1.7 variant.

Moderna also reported Preliminary results Researchers have seen reduced protection against the B.1.351 mutant, but from laboratory studies showing that the vaccine protects against the B.1.1.7 mutant.

In Phase 3 clinical trials, vaccine makers Johnson & Johnson and Novavax said their vaccines Less effective in South Africa, B.1.351 Where variants are widespread.

While there are concerns about the emergence of SARS-CoV-2 mutants that can evade the immune system, Hatziioannou points out that the immune system has ways to deal with viruses other than the evasive antibodies.

In addition, some of the Phase 3 vaccine trials Like modana, Shows that the vaccine stimulates the immune system to produce high levels of antibodies. Often at higher levels than antibodies obtained by natural infection.

Therefore, the vaccine is effective against the virus, even if the mutant reduces the effectiveness of the antibody by a factor of 10. Jesse Bloom, PhD, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, New York Times..

People may also be protected from serious illness, even if the mutant reduces the overall effectiveness of the vaccine.

This seems to be the case with the Johnson & Johnson vaccine.Vaccine 85% effective Even in South Africa, for severe illness.

But vaccine makers are already preparing to update their vaccines to better ones Protect from variants, If necessary.

Reducing severe illness will still reduce hospitalization and mortality, even if people show mild symptoms.

Dr. Eric TopolThe director and founder of the Scripps Research Translational Institute, pointed out: twitter So far, six Phase 3 COVID-19 vaccine trials have been completed and no one has died of COVID-19.

“It is not a single death or hospitalization in the COVID-19 vaccine group of more than 75,000 participants,” he said.

Hatziioannou points out that the main goal of vaccine trials was not to prevent all infections, but to reduce more serious illnesses.

The primary endpoint of Moderna-NIAID and Pfizer-BioNTech was the prevention of symptomatological infections. For Johnson & Johnson, it was to prevent moderate or severe illness.

“You can achieve protection from serious illnesses without stopping the infection,” said Hatziioannou. [COVID-19] Vaccines protect you from the disease caused by these new mutants. “

You may not know how often you are re-infected with the coronavirus unless you start testing people more often at random. However, Sealphone believes that awareness of the risks is sufficient.

“It’s important to know that there is a surprisingly high reinfection rate,” he said. [should] Get vaccinated and continue to use masks and other infection prevention procedures to protect yourself and others. “