Repeated Leftover Serosurvey of SARS-CoV-2 IgG Antibodies in Greece, May to August 2020

Abstract

A serosurvey of IgG antibodies against SARS-CoV-2 was conducted in Greece between May and August 2020. It was designed as a cross-sectional survey and was repeated at monthly intervals. The leftover sampling methodology was used and a geographically stratified sampling plan was applied. Of 20,110 serum samples collected, 89 (0.44%) were found to be positive for anti-SARS-CoV-2 antibodies, with higher seroprevalence (0.35%) observed in May 2020. The highest seroprevalence was primarily observed in the “30–49” year age group. Females presented higher seroprevalence compared to males in May 2020 (females: 0.58% VS males: 0.10%). This difference reversed during the study period and males presented a higher proportion in August 2020 (females: 0.12% VS males: 0.58%). Differences in the rate of seropositivity between urban areas and the rest of the country were also observed during the study period. The four-month infection fatality rate (IFR) was estimated to be 0.47%, while the respective case fatality rate (CFR) was at 1.89%. Our findings confirm low seroprevalence of COVID-19 in Greece during the study period. The young adults are presented as the most affected age group. The loss of the cumulative effect of seropositivity in a proportion of previous SARS-CoV-2 infections was indicated.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection Fatality Rate Among Elderly Danes: A Cross-sectional Study on Retired Blood Donors

“…Our IFR estimate among older individuals was only slightly lower than the 6.9% recently reported from rural settings in Latin America [17]. These estimates for the elderly population are, as expected, much higher than previously reported estimates for all ages from Greece [18], China [19], and cruise ships [20] as well as the estimate we reported in the younger donor population [4].…”

How will the way we live look different in the wake of the COVID-19 pandemic? A nutrition survey in Greece

“…In total, 89 (3.94%) of the participants reported that they had, or currently have been diagnosed with COVID-19; of these, 36 were men (3.95%, mean age 33 (SD 13) years) and 53 were women (3.94%, age 32 (SD 16) years) (p-value for sex comparisons ¼ 0.82). The incidence of COVID-19 observed in this survey is in line (adjusted for period effect) with reports from seroepidemiological studies conducted in Greece during the past months (Bogogiannidou et al, 2020;Tsitsilonis et al, 2020).…”

SARS-CoV-2 Sero-Surveillance in Greece: Evolution over Time and Epidemiological Attributes during the Pre-Vaccination Pandemic Era

“…From March 2020 to present, an ongoing national initiative has been implemented in Greece, systematically monitoring the seroprevalence in leftover serum samples at monthly intervals, covering the vast majority of regional units in the country. Previously published reports indicate low percentages of seropositivity in Greece until August 2020 [ 6 , 7 ], which is in accordance with low levels of virus circulation until that period. Seroprevalence at a national scale had been consistently estimated to be lower than 0.5% for the period between March to August 2020, while the cumulative incidence of COVID-19 based on reported cases was approximately 0.1% by 30 August 2020.…”

“…The statistical analysis applied is based on the methodology that was applied for samples between March and August 2020 [ 6 , 7 ], with some modifications. Analysis was performed with the use of IMB SPSS Statistics V22.0 and Microsoft Excel.…”