Thankfully, we don’t just rely on antibodies for protection. Evasion from neutralising antibodies explains our failure to control reinfection by omicron variants. Omicron lineages have enough mutations to differentiate substantially from previous variants, and therefore evade existing antibodies. Burundi’s COVID-19 vaccination campaign acceleratesīut to persist, viruses like SARS-CoV-2 introduce random mutations in their genome when they replicate, aiming to continuously alter their proteins to escape immune recognition.Which lower-income countries saw the biggest COVID-19 vaccination coverage gains in 2022?.Can the “world’s first intranasal COVID vaccine” help spur booster uptake in India?.These Y-shaped molecules recognise intact proteins of the virus exterior and attach to them, preventing the virus from latching on to the cell receptor necessary for infection. The study’s observations, which treat protection against pre-omicron variants and omicron BA.1 separately, make sense when we consider how omicron variants differ from their predecessors.īy way of background, neutralising antibodies generated after previous viral infection are important to prevent subsequent virus entry to susceptible cells. It has generated sequential variants of concern, with increased transmissibility and capacity to evade our immune responses compared with the ancestral virus. ![]() Making sense of the findingsĪ couple of years is a long time for highly contagious respiratory viruses, and SARS-CoV-2 (the virus that causes COVID) has been no different. The results also revealed that protection against severe disease after natural infection was comparable to that received from two vaccine doses, for both pre-omicron and omicron BA.1 variants. ![]() Rather, it seems there was limited data available that followed people for long enough for the authors to be able to draw strong conclusions beyond this time frame. This isn’t to say that protection drops substantially after 40 weeks. When assessing severe disease, however, all variants showed sustained protection above 88% for 40 weeks. This was also the case for symptomatic infection.ĭata from long-term studies showed that protection against reinfection for pre-omicron variants dropped to 78.6% over 40 weeks, whereas for omicron BA.1 it dropped more rapidly to 36.1%. A previous infection provided moderate protection from reinfection with omicron BA.1 (45%), compared with stronger protection against pre-omicron variants (82%). They found previous infection was highly protective against reinfection with alpha, beta and delta variants, but less so against omicron BA.1. The authors evaluated protection against reinfection, symptomatic disease, and severe disease (defined as hospitalisation or death) separately. The analyses spanned studies from the beginning of the pandemic until September 2022, and looked primarily at the alpha, beta, delta and omicron BA.1 variants. ![]() The researchers aimed to assess if infection induced similar protection against reinfection with different variants, and if this waned differently over time. Studies looking at natural immunity in combination with vaccination (hybrid immunity) were excluded. These studies compared COVID risk among people who had been infected previously and those without a prior infection. The authors collected data from 65 studies across 19 countries, making it the largest review on this topic to date. ![]() Also, if we do catch COVID again, will the immunity we’ve acquired from this infection reduce the severity of the next one?Ī new study published in The Lancet set out to answer these questions, looking at the strength and duration of natural immunity by COVID variant. After a COVID infection, whether it’s a first, second, or even a third, many of us wonder how long we might be protected against a reinfection, and whether we’ll be susceptible to new variants.
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