If You Had the a Virus Last Year Can You Get It Again
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COVID reinfections surge during Omicron onslaught
Cases of coronavirus reinfection are increasing around the world. Credit: Carlo Allegri/Reuters
Since the Omicron variant of SARS-CoV-2 was first detected, the number of people reinfected with the coronavirus has been rising sharply — a trend that was not observed with previous variants. Researchers say that the new variant is probably driving the surge because it is able to evade the trunk's immune defences.
"The situation at present is actually different. We're talking about a variant with lots of allowed-evasive properties," says Laith Abu-Raddad, an infectious-disease epidemiologist at Weill Cornell Medicine–Qatar in Doha.
Studies have shown that the variant tin can outwit immunity induced by vaccination. At present Abu-Raddad and others are revealing how well Omicron can evade antibodies produced during previous SARS-CoV-ii infections. "The ability of Omicron to infect people with either vaccine- or infection-derived immunity is a primal role of what fabricated the recent surge so large," says Marm Kilpatrick, an infectious-disease researcher at the Academy of California, Santa Cruz.
Understanding reinfection rates is crucial for assessing "how infections might surge and if hospitals will be able to cope", says Catherine Bennett, an epidemiologist at Deakin University in Melbourne, Australia.
COVID-19 again
The first signs of Omicron'south immune-evasive properties came from data nerveless in South Africa, says Bennett. In November last year, researchers showed college-than-expected rates of reinfection compared with those of previous wavesane. Similar trends have now been documented elsewhere.
In England, more than 650,000 people accept probably been infected twice; most of them were reinfected in the by 2 months, co-ordinate to information collected past the Uk Wellness Security Agency (run into 'Rise reinfections'). The agency considers an infection a 'possible reinfection' if it took place at least three months later a previous i, simply does not confirm that these are separate instances through genetic sequencing of the virus. Before mid-November, reinfections accounted for about one% of reported cases of COVID-19, just the rate has now increased to around 10%.
The United kingdom Role for National Statistics in Newport has also seen a precipitous increase in possible reinfections in recent months, as part of its random sampling of households across the state. The survey counts a possible reinfection if iv months have passed since the previous one. The reinfection gamble was 16 times college between mid-December last yr and early January this twelvemonth when Omicron dominated, than in the 7 months leading up to Dec when Delta was the ascendant variant.
Such surveys could be underestimating the true charge per unit of reinfection because some infections go undiagnosed, and some could have happened sooner after the offset infection — especially in countries where cases of Omicron rapidly followed a Delta wave, says Bennett.
Multiple factors could explain the spike in reinfections, she says. With more than people now already exposed to the virus, at that place is a higher chance of seeing reinfections. Omicron'due south speedy spread also increases the chance. But the variant's ability to evade immunity is probably playing a part, says Bennett.
Allowed evasion
In a correspondence2 published in The New England Periodical of Medicine this month, Abu-Raddad and his colleagues measured the extent to which Omicron could evade immunity, as part of a nationwide study of infections in Qatar since the start of the pandemic. They found that although having previously been infected was around xc% effective at preventing an infection with the Alpha, Beta or Delta variants, it was but 56% effective against Omicron.
However, Abu-Raddad is encouraged past the results. Nearly reinfections occurred nigh 1 year autonomously, showing that a previous infection offers immunity for some time. And protection against astringent COVID-19 caused past Omicron remained loftier, at effectually 88%.
But Shabir Madhi, a vaccinologist at the University of the Witwatersrand in Johannesburg, Due south Africa, says that the report probably missed many infections that were asymptomatic or mild and were therefore not recorded, so it might be overestimating the effectiveness of a previous infection against Omicron. He expected much lower protection against infection. Laboratory studies have shown that Omicron can successfully evade virus-blocking antibodies generated from earlier variants, which are a good proxy for protection against infection3 , 4.
Ultimately, Abu-Raddad says that studying reinfections will assistance researchers to empathize what SARS-CoV-ii's transition to an endemic virus will wait similar.
References
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Source: https://www.nature.com/articles/d41586-022-00438-3
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