COVID-19 vaccine uptake and associated risk factors among first antenatal care attendees in Zambia, 2021-2022: a repeated cross-sectional study (preprint)

Introduction:   Pregnant women are considered a high-risk group for COVID-19, and a priority for vaccination. Routine antenatal (ANC) care provides an opportunity to track trends and factors associated with vaccine uptake. We sought to evaluate COVID-19 vaccine uptake among pregnant women attending ANC in Zambia.   Methods  We conducted a repeated cross-sectional study in 39 public health facilities in four districts in Zambia from September 2021 to September 2022. Pregnant women who were aged 15-49 years were enrolled during their first ANC visit. Every month, ~20 women per facility were interviewed during individual HIV testing and counseling. We estimated vaccine uptake as the proportion of eligible participants who self-reported having received the COVID-19 vaccine.   Results   A total of 9,203 pregnant women were screened, of which 9,111 (99%) were eligible and had vaccination status. Of the 9,111 included in the analysis, 1,818 (20%) had received the COVID-19 vaccine during the study period, with a trend of increasing coverage with time (0.5% in September 2020, 27% in September 2022). Conversely, 3,789 (42%) reported not being offered a COVID-19 vaccine. We found that older age, education, employment status, and prior COVID-19 infection were significantly associated with vaccine uptake.     Conclusion  COVID-19 vaccine uptake among pregnant women was lower than estimates from the general population (27% across the four districts in September 2022), pointing to missed opportunities to protect this high-risk group. ANC visits were a viable point for conducting COVID-19 surveillance. Incorporating the vaccine as part of the routine ANC package might increase coverage in this group.

Factors associated with SARS-CoV-2 among persons living with HIV in Zambia: Analysis of three concurrent SARS-CoV-2 prevalence surveys conducted in July 2020 in six districts of Zambia (preprint)

People living with HIV (PLHIV) are a unique population because of their altered immune systems and taking antiretroviral therapy (ART) that may modify risk of SARS-CoV-2. Evidence from sub-Saharan African countries suggests that, despite not having higher SARS-CoV-2 infection prevalence than HIV-negative persons, PLHIV suffer worse COVID-19 outcomes. We assessed the prevalence of SARS-COV-2 infection by HIV status in Zambia in July 2020. We analyzed data from three different concurrent SARS-CoV-2 prevalence surveys (household, outpatient-department, and health-worker) conducted in six districts of Zambia in July 2020. Information on demographics and medical history was collected. Nasopharyngeal swabs were used to screen for SARS-CoV-2 RNA using polymerase-chain-reaction (PCR) and blood specimens were screened for SARS-CoV-2 virus-specific antibodies using an enzyme-linked-immunosorbent-assay (ELISA). Test-specific SARS-CoV-2 prevalence was calculated. Multilevel logistic regression models were used to measure test-specific adjusted odd ratios (aORs) of SARS-CoV-2 positivity by HIV status, controlling for demographic and medical history. We analysed the outcomes of the two different tests separately. Among 7,092 participants, 4,717 (66.5%) consented to blood-draw and 4,642 (65.5%) consented to nasopharyngeal swab. Overall SARS-CoV-2 positivity was 9.4% by PCR and 3.8% by ELISA. SARS-CoV-2 prevalence detected by PCR was higher among PLHIV than HIV-negative respondents (12.4% vs 9.1%, respectively, OR: 1.4, 95% confidence intervals [CI]: 1.0-1.9) and lower by ELISA (1.9% vs 3.9%, respectively, OR: 0.5, 95%CI: 0.2-0.9). Among PLHIV, not being on ART was an independent predictor of SARS-CoV-2 PCR positivity (aOR: 5.24,95% CI: 1.19-22.22) but did not have a significant effect on ELISA results. During the first COVID-19 wave in Zambia, PLHIV were more likely to be acutely infected with SARS-CoV-2 but less likely to be seropositive than participants without HIV. Intervention programs could focus on early access to COVID-19 vaccinations, testing and ART might reduce COVID-19 morbidity among PLHIV.

SARS-CoV-2 Mortality Surveillance among Community Deaths brought to University Teaching Hospital Mortuary in Lusaka, Zambia, 2020 (preprint)

Introduction During March-December 2020, Zambia recorded 20,725 confirmed COVID-19 cases, with the first wave peaking between July and August. Of the 388 COVID-19-related deaths occurring nationwide, most occurred in the community. We report findings from COVID-19 mortality surveillance among community deaths brought to the University Teaching Hospital (UTH) mortuary in Lusaka. Methods In Zambia, when a person dies in the community, and is brought into a health facility mortuary, they are recorded as ‘brought in dead’ (BID). The UTH mortuary accepts persons BID for Lusaka District, the most populated district in Zambia. We analyzed data for persons BID at UTH during 2020. We analyzed two data sources: weekly SARS-CoV-2 test results for persons BID and monthly all-cause mortality numbers among persons BID. For all-cause mortality among persons BID, monthly deaths during 2020 that were above the upper bound of the 95% confidence interval for the historic mean (2017-2019) were considered significant. Spearman’s rank test was used to correlate the overall percent positivity in Zambia with all-cause mortality and SARS-CoV-2 testing among persons BID at UTH mortuary. Results During 2020, 7,756 persons were BID at UTH (monthly range 556-810). SARS-CoV-2 testing began in April 2020, and through December 3,131 (51.9%) of 6,022 persons BID were tested. Of these, 212 (6.8%) were SARS-CoV-2 positive with weekly percent test positivity ranging from 0-32%, with the highest positivity occurring during July 2020. There were 1,139 excess persons BID from all causes at UTH mortuary in 2020 compared to the 2017-2019 mean. The monthly number of persons BID from all causes was above the upper bound of the 95% confidence interval during June-September and December. Conclusion Increases in all-cause mortality and SARS-CoV-2 test positivity among persons BID at UTH mortuary corresponded with the first peak of the COVID-19 epidemic in June and August 2020, indicating possible increased mortality related to the COVID-19 epidemic in Zambia. Combining all-cause mortality and SARS-CoV-2 testing for persons BID provides useful information about the severity of the epidemic in Lusaka and should be implemented throughout Zambia.