Seroprevalence of Anti-SARS-CoV-2 Antibodies Following the Omicron BA.1 Wave

Abstract

We conducted a seroprevalence study using convenient residual sera samples from the Slovenian population collected after the end of the Omicron BA.1 pandemic wave. Serum samples were tested for spike glycoprotein (anti-S) and nucleocapsid protein (anti-N) antibodies. Participants’ data regarding confirmed infection and vaccination was obtained from national registries. Anti-S antibodies were detected in 2439 (84.1%) of 2899 sera from persons aged 0–90 years, with the lowest prevalence in the 0–17 age group. The proportion of anti-N positives was the lowest in the ≥70 age group. The proportion of anti-N positives was significantly higher among participants with confirmed past infection and among those who had never been vaccinated. In participants who had not been notified as infected and who had never been vaccinated, the seroprevalence of anti-S and anti-N antibodies was 53% and 35.5%, respectively. From the time of serum collection to mid-November 2022, 445 participants (15.3%) tested positive for SARS-CoV-2, with higher odds in seronegative participants, participants in the 40–59 age group, and those without notified previous infection. Vaccination status and gender had no significant effects on infection risk. This study underlines the importance of serosurveys in understanding the development of the pandemic.

Seroprevalence of severe acute respiratory syndrome coronavirus 2 N antibodies between December 2021 and march 2023 in Japan

“…The seroprevalence of antibodies against the N protein in Japan was reported to be 3.5% in February to March 2022 [ 1 ] and cumulative confirmed cases as of May 2023 exceeded 33.8 million (28.2% of the Japanese population). Unlike other countries where seroprevalence rates exceeded 50% [ 3 , 4 , 6 – 10 ], most of the Japanese population had not been infected at that time, suggesting the possibility of future SARS-CoV-2 epidemics in Japan.…”

“…As of May 2023, 760 million cases including 6.9 million deaths have been reported to the World Health Organization (https://covid19.who.int/). The threat of SARS-CoV-2 is subsiding as most people have acquired sufficient antibodies through vaccination and/or infection to prevent severe COVID-19; more than 80% of the populations of major industrialized countries have antibodies against the S protein induced by vaccination and/or infection [1][2][3][4][5]. In contrast, the seroprevalence of antibodies against the N protein elicited by SARS-CoV-2 infection ranged from 44.4% to 80.2% in the United States, England, Spain, Slovenia, Switzerland, and Thailand between March and November 2022 after the emergence of the omicron variants [3,4,[6][7][8][9][10].…”

Anti-S Antibodies Against SARS-CoV-2 Infection Among Four Types of Vaccines in Malaysia

“…This memory response contributes to sustained antibody levels. 9,[17][18][19] After some time from the initial COVID-19 vaccination, the levels of antibodies that provide protection against the virus may start to decline. This is according to the studies done during the early phase of the vaccination worldwide.…”

“…This is according to the studies done during the early phase of the vaccination worldwide. 14,15,18,20,21 Thus, the suggestion to take booster vaccination was introduced and implemented. 14,15,22 Booster doses of COVID-19 vaccines are designed to provide an additional level of protection against the virus, especially in the face of emerging variants and waning immunity over time.…”

Comparing COVID-19 severity in patients hospitalized for community-associated Delta, BA.1 and BA.4/5 variant infection

“…After 2 years of the epidemic the level of testing for SARS-CoV-2 infection was dramatically reduced in Slovenia, rendering the estimation of the true proportion of those who had been infected at least once before a SARS-CoV-2 infection that required hospitalization difficult. A population-based study carried out in the country showed that prior to the Omicron BA.4/5 predominant wave, there was a 35.5% seroprevalence of SARS-CoV-2 anti-N antibodies in participants who had never been officially notified as infected ( 34 ).…”