COVID-19 infections through the Omicron wave in unvaccinated US adults
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In a current examine posted to the medRxiv* preprint server, researchers assessed the incidence of extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections through the prevalence of the SARS-CoV-2 Omicron variant.

Study: Incidence of SARS-CoV-2 an infection amongst unvaccinated US adults through the Omicron wave. Image Credit: CROCOTHERY/Shutterstock

As of April 2022, whereas 23% of the full US inhabitants had not obtained their coronavirus illness 2019 (COVID-19) vaccine, 99% of the unvaccinated adults had anti-SARS-CoV-2 antibodies. However, additional analysis is required to evaluate the safety supplied by these antibodies in opposition to novel SARS-CoV-2 variants.

About the examine

In the current examine, researchers characterised the COVID-19 infections amongst adults residing within the US through the SARS-CoV-2 Omicron (B.1.1.529) wave.

The examine comprised adults who had no historical past of SARS-CoV-2 vaccination between 11 September 2021 and eight October 2021. The crew carried out anti-SARS-CoV-2 spike (S) serological testing between 23 September 2021 and 5 November 2021 earlier than the prevalence of SARS-CoV-2 Omicron infections.

Furthermore, the members had been labeled based mostly on the neutralization antibody titers. The members had been required to finish a follow-up questionnaire to acquire data associated to the take a look at standing and signs of COVID-19, comparable to COVID-19 positivity, COVID-19 suspicion with no optimistic COVID-19 take a look at, or neither suspected COVID-19 an infection nor optimistic take a look at. The signs reported by the members within the questionnaire had been labeled as both gentle, average, extreme, or none.     


The examine comprised 843 unvaccinated people who displayed anti-receptor binding area (RBD) evaluated two months earlier than the prevalence of the SARS-CoV-2 Omicron variant. Among these, the median age was 48 years, together with 54% girls and 83% White individuals. Moreover, 37% of the full members reported a optimistic COVID-19 take a look at end result, whereas 60% had anti-RBD antibodies earlier than the Omicron wave. Notably, 82% of the examine cohort reported no common masks utilization when in public.

Among the unvaccinated individuals, 35% had no pre-existing antibodies and reported a historical past of COVID-19 an infection, whereas 12% had a suspected however unconfirmed COVID-19 throughout Omicron prevalence. On the opposite hand, 12% of the unvaccinated members who had pre-existing antibodies reported COVID-19 historical past, whereas 15% reported suspected however unconfirmed COVID-19 within the interval of Omicron prevalence. Among individuals with 0.8 to 1000 U/mL anti-RBD antibodies, 12% had confirmed and 16% had suspected COVID-19 analysis, whereas these with anti-RBD 1000 U/mL or increased included 9% with confirmed and seven% with suspected COVID-19.

The crew additionally famous that people with out antibodies had a 67% increased chance of testing COVID-19 optimistic as in comparison with individuals with antibodies. Among the COVID-19-confirmed people, individuals with antibodies had a shorter length of signs than these with no antibodies. Moreover, the variety of antibody-negative people was increased amongst individuals who examined COVID-19 optimistic and had suspected however unconfirmed COVID-19.


Overall, the examine findings confirmed that anti-RBD antibodies present in unvaccinated wholesome people had been related to a big discount within the threat of SARS-CoV-2 reinfection and shorter length of signs as in comparison with individuals with none anti-RBD antibodies. The researchers imagine that whereas the reported illness severity for SARS-CoV-2 Omicron infections is decrease than for different variants, COVID-19-hospitalized sufferers are nonetheless at vital threat of experiencing extreme sickness and demise.

*Important discover

medRxiv publishes preliminary scientific reviews that aren’t peer-reviewed and, due to this fact, shouldn’t be thought to be conclusive, information medical observe/health-related habits, or handled as established data.

Journal reference:

  • Alejo, J. et al. (2022) “Incidence of SARS-CoV-2 infection among unvaccinated US adults during the Omicron wave”. medRxiv. doi: 10.1101/2022.05.27.22275630. material/10.1101/2022.05.27.22275630v1

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