What is a COVID-19 secondary infection? What effect does the emergence of new strains have on secondary infections?

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Secondary COVID-19 infection refers to a situation in which a person is infected with the new crown virus and is infected again after recovering. Even if a history of previous infection provides some protection, the emergence of new variants of the virus may lead to immune escape, triggering secondary infection. For now, vaccinations, wearing masks, maintaining 1 meter of social distancing, and trying to avoid being in crowded and poorly ventilated indoor spaces are still the best way to protect yourself.

The investigator | Han Yue, a postdoctoral fellow in virology at the University of Cambridge

With the emergence of new epidemics in many parts of the country, many people have returned to the state of working from home. Now that Aomi Kerong has become the mainstream new coronavirus strain in the world, the high infectivity of Aomi Kerong makes everyone have to pay attention to a question: what is the chance of secondary infection of the new crown virus?

1. What is a secondary infection?

We first need to define what a secondary infection is. Generally speaking, the new crown secondary infection (re-infection) refers to the situation in which a person is infected with the new crown virus, recovers, and is re-infected.

Second, what is the chance of secondary infection?

In a survey in the U.S. state of New York, researchers found that as of March 20, 2022, 200655 cases of secondary infection had been reported, representing approximately 3.9 percent of all COVID-19 cases reported in New York State to date [1]. It is worth noting that this number has risen significantly after the outbreak in Omiquerong, with 170104 of all secondary infections occurring after 13 December 2021.

A UK study also noted that as of January 9 this year, there were about 425,890 possible cases of secondary infection in the UK, and some of them were also related to the outbreak of Omiljung: 109936 of all secondary infections were detected in the week before 9 January, accounting for almost 11% of all cases in that week [2]. However, the researchers also point out that this number may not be accurate, because in the UK, many first-time infections may not be counted because few people in the community are able to detect in the first wave. In a Bulgarian study, a total of 4106 patients were observed to be infected more than once by analyzing three major outbreaks from March 2020 to December 2021, of which 31 patients were infected 3 times and 1 patient was even infected 4 times. At the end of 2021, the number of secondary infections increased dramatically during the pandemic caused by the Delta mutation [3].

Third, the emergence of secondary infections or even multiple infections, the most important reason for the current situation is the emergence of new coronavirus variants

Usually, after the first infection with the new coronavirus (or after vaccination), our body improves T cell immunity, and memory B cells that secrete antibodies enhance the response to spike proteins and the effectiveness of neutralizing antibodies. Although antibodies excited by Pfizer and Modena's mRNA vaccines have a cross-neutralizing effect on alpha strains (B.1.1.7) and beta strains (B.1.351) variants, evidence from molecular biology also suggests that genetically different strains of the virus (e.g., Delta and Omikeron) or new variants (e.g., BA.1, BA.2) may evade the immune system, whether through natural infection or vaccination [4]. This was confirmed by the increase in the number of patients with secondary infections in the early days of Delta and Omikejong.

So can the same patient be infected twice by Ami kerong? The bad news is that this is likely to happen. The BA.2 branch, as a new mutant strain of Opmi kerong, has now become the main infection strain for new cases in many countries and regions. Previously, Danish scientists confirmed that the BA.2 variant can also infect patients who have previously been infected by Omikeron. The good news is that this condition is uncommon, and there are no more severe symptoms following infection [5], with significantly lower hospitalization rates in most studies of secondary infections at all ages. Other studies that did not reach definitive conclusions were also largely because the sample size was too small to draw definitive conclusions.

The coronavirus is still mutating, and the constant emergence of new strains may increase the risk of secondary infection. For now, vaccinations, wearing masks, maintaining 1 meter of social distancing, and trying to avoid being in crowded and poorly ventilated indoor spaces are still the best way to protect yourself.

bibliography

[1]https://coronavirus.health.ny.gov/covid-19-reinfection-data

[2]https://www.theguardian.com/world/2022/jan/21/covid--how-likely-are-you-to-catch-virus-multiple-times

[3]https://www.medrxiv.org/content/10.1101/2022.03.11.22271527v1.full

[4]https://www.nature.com/articles/s41598-022-05325-5

[5]https://www.cnbc.com/2022/02/25/covid-transmissibility-severity-reinfection-of-omicron-bapoint2-subvariant.html

This article was edited by Ambergchen