tetano
Editor, Senior Moderator
BMC Public Health
. 2022 Oct 25;22(1):1961.
doi: 10.1186/s12889-022-14381-5.
Pre-vaccination RT-PCR negative contacts in workplace settings show high, SARS COV-2 neutralizing antibody levels
Ridma P Karunathilake[SUP] 1 [/SUP], Sameera Hewage[SUP] 2 [/SUP], Gihani Vidanapathirana[SUP] 1 3 [/SUP], Athula Kumara[SUP] 1 [/SUP], Prabhath Ranasinghe[SUP] 4 [/SUP], Faseeha Noordeen[SUP] 1 [/SUP], Indika Gawarammana[SUP] 5 [/SUP], Champa N Ratnatunga[SUP] 6 [/SUP]
Affiliations
Abstract
Background: Asymptomatic SARS-CoV-2 infection occurring in RT-PCR negative individuals represent a poorly characterized cohort with important infection control connotations. While household and community-based studies have evaluated seroprevalence of antibody and transmission dynamics in this group, workplace-based data is currently unavailable.
Methods: A cohort study was carried out in July 2021, during and immediately following the peak of the 3[SUP]rd[/SUP] wave of COVID-19 in Sri Lanka, prior to mass vaccination. A total of 92 unvaccinated individuals between the ages of 17-65 years were purposively sampled from an office and two factory settings. The selected cohort that had been exposed to RT-PCR positive cases in the workplace was tested RT-PCR negative. Serological samples collected six weeks post exposure were tested for anti-SARS-CoV-2 neutralizing antibody.
Results: The seroprevalence for SARS-CoV-2 specific neutralizing antibodies in the overall cohort was 63.04% (58/92). Seroprevalences in the office setting, factory setting 1 and factory setting 2 were 69.2% (9/13), 55.7% (34/61) and 83.33% (15/18), respectively. Primary risk factor associated with seropositivity was face to face contact with no mask for > 15 min (p < 0.024, Odds Ratio (OR); 5.58, 95%CI;1.292- 25.65). Individuals with workspace exposure had significantly higher levels of neutralizing antibodies than those who did not (percentage neutralization in assay 63.3% (SD:21)vs 45.7% (SD:20), p = 0.0042), as did individuals who engaged socially without protective measures (62.4 (SD:21.6)% vs 49.7 (SD:21)%, p = 0.026).
Conclusion: There was a high seroprevalence for SARS-CoV-2 specific neutralizing antibodies among RT-PCR negative contacts in workplace settings in Sri Lanka. Higher levels of transmission of SARS-CoV-2 infection than estimated based on RT-PCR positive contact data indicate need for targeted infection control measures in these settings during future outbreaks.
Keywords: COVID-19; Neutralizing antibodies; PCR negative contacts; Risk factors; Workplace settings.
. 2022 Oct 25;22(1):1961.
doi: 10.1186/s12889-022-14381-5.
Pre-vaccination RT-PCR negative contacts in workplace settings show high, SARS COV-2 neutralizing antibody levels
Ridma P Karunathilake[SUP] 1 [/SUP], Sameera Hewage[SUP] 2 [/SUP], Gihani Vidanapathirana[SUP] 1 3 [/SUP], Athula Kumara[SUP] 1 [/SUP], Prabhath Ranasinghe[SUP] 4 [/SUP], Faseeha Noordeen[SUP] 1 [/SUP], Indika Gawarammana[SUP] 5 [/SUP], Champa N Ratnatunga[SUP] 6 [/SUP]
Affiliations
- PMID: 36284261
- DOI: 10.1186/s12889-022-14381-5
Abstract
Background: Asymptomatic SARS-CoV-2 infection occurring in RT-PCR negative individuals represent a poorly characterized cohort with important infection control connotations. While household and community-based studies have evaluated seroprevalence of antibody and transmission dynamics in this group, workplace-based data is currently unavailable.
Methods: A cohort study was carried out in July 2021, during and immediately following the peak of the 3[SUP]rd[/SUP] wave of COVID-19 in Sri Lanka, prior to mass vaccination. A total of 92 unvaccinated individuals between the ages of 17-65 years were purposively sampled from an office and two factory settings. The selected cohort that had been exposed to RT-PCR positive cases in the workplace was tested RT-PCR negative. Serological samples collected six weeks post exposure were tested for anti-SARS-CoV-2 neutralizing antibody.
Results: The seroprevalence for SARS-CoV-2 specific neutralizing antibodies in the overall cohort was 63.04% (58/92). Seroprevalences in the office setting, factory setting 1 and factory setting 2 were 69.2% (9/13), 55.7% (34/61) and 83.33% (15/18), respectively. Primary risk factor associated with seropositivity was face to face contact with no mask for > 15 min (p < 0.024, Odds Ratio (OR); 5.58, 95%CI;1.292- 25.65). Individuals with workspace exposure had significantly higher levels of neutralizing antibodies than those who did not (percentage neutralization in assay 63.3% (SD:21)vs 45.7% (SD:20), p = 0.0042), as did individuals who engaged socially without protective measures (62.4 (SD:21.6)% vs 49.7 (SD:21)%, p = 0.026).
Conclusion: There was a high seroprevalence for SARS-CoV-2 specific neutralizing antibodies among RT-PCR negative contacts in workplace settings in Sri Lanka. Higher levels of transmission of SARS-CoV-2 infection than estimated based on RT-PCR positive contact data indicate need for targeted infection control measures in these settings during future outbreaks.
Keywords: COVID-19; Neutralizing antibodies; PCR negative contacts; Risk factors; Workplace settings.