Table 1. Seroprevalence of IgG to SARS-CoV-2 among mothers attending antenatal care in Kenyatta National Hospital (KNH), Nairobi.
| 30th July– 25th August 2020 | 27th Jan- 11th March 2021 | 7th September-19th October 2021 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| KNH | Seroprevalence | Adjusted seroprevalence | Seroprevalence | Adjusted seroprevalence | Seroprevalence | Adjusted seroprevalence | |||||||
| Nairobi | n / N | % | % | 95% CI | n / N | % | % | 95% CI | n / N | % | % | 95% CI | |
| All | 91 / 196 | 46.4 | 49.9 | 42.1–58.2 | 80 / 265 | 30.2 | 32.1 | 26.2–38.4 | 193 / 245 | 78.8 | 84.9 | 78.3–91.5 | |
| Age | |||||||||||||
| 17–29 years | 39 / 93 | 41.9 | 44.9 | 33.8–56.9 | 28 / 101 | 27.7 | 29.6 | 20.7–39.2 | 82 / 101 | 81.2 | 87.2 | 77.9–95.7 | |
| 30–45 years | 44 / 90 | 48.9 | 52.5 | 41.1–63.7 | 47 / 141 | 33.3 | 35.7 | 27.3–44.3 | 107 / 139 | 77.0 | 83.0 | 74.0–91.7 | |
| Trimester | |||||||||||||
| First | 7 / 17 | 41.2 | 44.9 | 21.2–70.1 | 27 / 83 | 32.5 | 35.0 | 24.1–46.4 | 48 / 60 | 80.0 | 85.5 | 73.0–96.1 | |
| Second | 21 / 53 | 39.6 | 42.9 | 29.8–57.4 | 34 / 106 | 32.1 | 34.5 | 25.1–44.3 | 77 / 96 | 80.2 | 86.1 | 76.0–95.5 | |
| Third | 58 / 114 | 50.9 | 54.7 | 44.6–64.6 | 18 / 75 | 24.0 | 25.8 | 16.4–37.0 | 64 / 84 | 76.2 | 81.6 | 71.2–91.7 | |
| Any symptoms in last month* | |||||||||||||
| Yes | 7 / 12 | 58.3 | 61.2 | 33.3–86.1 | 3 / 18 | 16.7 | 20.8 | 5.5–42.2 | 80 / 106 | 75.5 | 81.2 | 71.3–90.5 | |
| No | 78 / 172 | 45.3 | 48.7 | 40.2–57.5 | 77 / 247 | 31.2 | 33.3 | 26.9–40.0 | 113 / 139 | 81.3 | 87.5 | 79.3–95.1 | |
| Population density of sub-county of residence | |||||||||||||
| <20000/km2 | 44 / 97 | 45.4 | 48.8 | 38.1–59.4 | 29 / 104 | 27.9 | 29.8 | 20.6–39.8 | 86 / 102 | 84.3 | 90.6 | 82.2–97.9 | |
| 20-81000/km2 | 39 / 79 | 49.4 | 53.1 | 41.0–65.7 | 40 / 124 | 32.3 | 34.6 | 25.9–44.1 | 85 / 115 | 73.9 | 79.5 | 70.3–88.5 | |
| COVID-19 vaccine status† | |||||||||||||
| Vaccinated | - | - | - | - | - | - | - | - | 30 / 31 | 96.8 | 96.1 | 86.2–99.9 | |
| Unvaccinated | - | - | - | - | - | - | - | - | 163 / 214 | 76.2 | 82.1 | 75.1–89.2 | |
* Women were asked about the full list of COVID-19 symptoms as per the MOH COVID-19 screening form i.e. fever/ chills, general weakness, cough, sore throat, runny nose, shortness of breath, diarrhoea, nausea/ vomiting, headache, irritability/ confusion, pain (muscular/ chest/ abdominal/ joint).
† Vaccination status (at least one dose) was not available for the first two rounds of data collection, vaccination began in Kenya in March 2021 and at first targeted specific groups only, we assume that the vaccine coverage among women attended antenatal care between 27th Jan-11th March was 0%.
Variations in seroprevalence by any of the explanatory variables were not statistically significant in any time period when tested with chi2 test.