Changes in Childhood Immunizations and Intermittent Preventive Malaria Treatment in a Peripheral, Referral Immunization Center During the First 12 Months of COVID-19 Pandemic in Sierra Leone, Western Africa

Abstract

Background: There is increasing evidence that the COVID-19 pandemic disrupted childhood immunization services. However, detailed reports on immunizations and preventive antimalarial prophylactic treatments delivered and how the trends changed in referral centers in low-income countries are still missing.

Methods: We performed a retrospective cross-sectional study. Data for vaccinations administered to children <5 years of age, according to the local vaccination schedule, were extracted from the official records of the Kent Community Health Post, Sierra Leone, in the period between April 2019 and March 2021. We compared the vaccinations performed in the first year, considered as a pre-Covid period, with the second year, post-Covid period. Both the period was then divided in four trimester each and the same analysis was operated for each trimester. A Chi-square goodness of fit test was performed to compare the number of vaccinations performed both in the 2 years and in the 8 trimesters.

Findings: Seven thousand two hundred and eighty-three vaccinations were administered: 4,641 in the period between April 2019 and March 2020 and 2,642 between April 2020 and March 2021. The drop in immunizations performed began as soon as the first cases were described in China. The drops were statistically significant when the first three trimesters of the two study periods were compared, while no statistically significant differences were observed for all the vaccines performed in the 4th trimesters. Vaccines administered at birth (BCG) were less affected compared to booster vaccinations.

Conclusions: Immunizations administered in a referral health center in Sierra Leone significantly declined during the pandemic. Although the decline was less pronounced in the last months of the pandemic, we don't think that the small increase would indicate the recovery of previously missed vaccinations. These findings open new public health challenges for the coming years.

Keywords: COVID-19; Sierra Leone; children immunization; pandemic; vaccines.

Figure 1

(A) Total number of immunizations delivered during the pre- and post-pandemic study periods. The data shows the absolute number of vaccines performed in the first and second year analyzed. In 2020 the number of vaccines performed appears visibly reduced and the different vaccines have undergone different deflections with the less affected which seem to be those performed at birth (BCG and OPV0) and IPTI 1 and 2. (B) Overall trend of the administered immunizations according to local SARS-CoV-2 cases and the first detection of SARS-CoV-2 in China. The figure shows how clearly immunizations dropped as soon as the first cases have been notified, before the first cases detected in Sierra Leone. The arrow shows the period in which the first cases were described in China.

Figure 2

Differences in the number of vaccinations performed per trimester in the 2 years. The figure shows the analysis per trimester; the 2 years studied have been divided in eight trimesters, four per year. The graph shows on the abscissa line the different vaccines studied and on the line of the ordinates the differences in percentage between the vaccines performed in the first and in the second year. Different vaccines showed different deflections with the first and the second trimester most affected for most vaccinations.

Figure 3

Comparison between BCG and PENTA1, PENTA2, and PENTA3 in the different trimesters. The figure compares the difference between the 2 years of a vaccine performed at birth (BCG) with the difference between the 2 years of three vaccines administered at different time-points (PENTA1, PENTA2, and PENTA3). On the ordinates we reported the differences in absolute number between the vaccines performed in the first and in the second year for each trimester. Although the BCG vaccine shows a generally minor reduction than all the three PENTA, this reduction becomes statistically significant only for the PENTA3 in the first and in the third trimester.