Why do people who haven’t had COVID cause new infections

The number of people who have not yet tested positive for COVID-19 is very low globally. This is an increasingly small minority, which until last Thursday included, for example, the President of the United States, Joe Biden, who had just contracted the infection for the first time in the third year of the pandemic.

According to figures from the UK Health Security Agency (UKHSA), About 15% of people in England have not had COVID-19.

But the most striking fact is that in the current wave, driven by the BA.4 and BA.5 sub-variables of Ómicron, this minority group still accounts for 55% of new infections.

How might this much smaller population contribute to new disease outbreaks? This is the question that specialists ask the most.

And just as SARS-CoV-2 has used them since its inception, Doubts are more than certainties.

Is that, In theory, in a pandemic the proportion of new infections is expected to drop from 100% in the first few days to a much smaller number as the virus eventually penetrates all areas of society.

It often happens that the only people not exposed are infants and young children. However, going to the last wave of COVID in England, the UKHSA estimated that more than 10 million people had not yet been infected.

The decline in infections for the first time may not be smooth as the epidemic spreads. The paper published that people’s behavior (that is, if they protect or reduce social contacts), their immunity and new variables influence this downward trend. Watchman.

And although 55% of COVID infections in England are “for the first time”, this is the lowest level since the beginning of the pandemic, with the exception of the peak of the first wave of Omicron, which was fueled by the BA.1 variant last December. .

I saw another way: 45% of cases are now re-infected, and that number is the highest ever. Experts say there are good reasons why injuries first appear to be more common than the data suggests. The first encounter with COVID is often the worst, while subsequent infections are often the mildest. Across the population, this can lead to awareness: Many people with their second, third, or fourth infection may not realize that they have contracted the virus again and are going through the disease without symptoms.

Graham Medley, Professor of Infectious Disease Modeling at the London School of Hygiene and Tropical Medicine, analyzes: “If an infection after the first is less likely to be symptomatic, or less likely to be seen by the public as a ‘worthy test’, there will be many more people who will be infected. Again but they don’t realize it, so the first infection is more likely to be diagnosed and reported.

Along these lines, clues as to why slightly more starters are now infected than in the first wave of Omicron can be found in who contracted the virus and when.

According to UKHSA surveillance data, the first wave of Omicron caused higher case rates among people in their 20s, 30s and 40s, but much lower in the elderly. The nation braced for a tidal wave from Omicron, as Boris Johnson called it at the time.

And when the next waves came, fueled by BA.2 in March and double action BA.4 and BA.5 in June, young masses were well protected from recent infection as well as vaccination.

According to a study conducted in Qatar, A recent infection with BA.1 gives a person approximately 80% protection against BA.4 or BA.5. In the BA.2 and BA.4/BA.5 waves, injuries were significantly higher in the older age groups, who were more likely to be beginners, with higher rates of infection in those over 60 years of age.

Another factor that may have influenced – in the opinion of specialists – is that After the first wave of microns, care measures to curb the virus, such as working from home and the mandatory use of masks inside the home, were removed. Additionally, most free trials and self-isolation requirements have been removed.

There is another element that explains the situation because When older people get the virus, they pass it on to other people of the same age, who are more likely to be beginners like themselves. For Bill Hanage, assistant professor of epidemiology at Harvard University, this is interpreted as two separate outbreaks.

In one group several people were vaccinated but only recently had BA.1 or BA.2, giving them strong ‘hybrid immunity’. If a member carries the infection to group A, it can only go that far.

But it’s a different story if this happened at the Bridge Club for people over 70, according to specialists. There, an infected player is more likely to pass the infection on to someone who has not been infected before and whose protection against infection is not strong. Then they will most likely pass it on to other starters.

“Introduction BA.5 is more likely to spread well within these previously uninfected groups Hanage was analyzed. Because of the increased risk of serious illness in the elderly, even in those who have been vaccinated, we can expect the severe consequences of this infection to be more numerous than if it occurred in younger people who were already infected.”

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