Doha – A recent groundbreaking seroepidemiological study conducted in Morocco’s Casablanca-Settat region has shed light on the effectiveness of COVID-19 vaccines administered in the country.
The study, published in the esteemed journal Scientific Reports on April 3, was conducted by a team of esteemed experts that included Moroccans. The study found that over 96% of vaccinated individuals have developed antibodies against SARS-CoV-2, indicating a strong humoral immune response to the various vaccines.
The cross-sectional study, which involved 10,669 participants, was carried out across 16 provinces in the Casablanca-Settat region from February to June 2022. Participants received either two doses of Sinopharm, AstraZeneca, Pfizer-BioNTech, or a single dose of the Johnson & Johnson’s Janssen vaccine.
The study found that the overall percentage of people with antibodies was 96%, and after adjusting for test performance, it was estimated at 96.2%. The percentages for each vaccine brand were similar, with 96% for Sinopharm, 97% for AstraZeneca, 98.5% for Pfizer-BioNTech, and 98% for Johnson & Johnson.
However, the Pfizer-BioNTech vaccine showed the highest percentage of people with antibodies at 98.5%. The study also found that the Pfizer-BioNTech vaccine produced the highest levels of antibodies among the four vaccines studied.
The study revealed that certain factors influenced the immune response to vaccination. Older participants, women, those with a history of previous COVID-19 infection, and those with certain chronic diseases were more likely to have antibodies among the AstraZeneca and Sinopharm vaccine groups.
Interestingly, the study found that participants vaccinated with AstraZeneca and Sinopharm who had chronic diseases showed a stronger response to vaccination compared to those without these conditions. In contrast, no significant differences were observed among Pfizer-BioNTech vaccinated participants.
The study’s authors emphasize the importance of these findings, particularly in the context of Morocco’s national vaccination campaign.
This was launched on January 28th, 2021, based on short-term randomized controlled trials that showed efficacy against symptomatic disease ranging from 62–96% after the second dose.
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The authors also note that while the published trial efficacy data seem to justify the emergency use of COVID-19 vaccines in Morocco, it is crucial to conduct further studies among vaccinated populations.
They state, “serological studies remain a useful tool to evaluate the implementation of vaccination campaigns and monitor population-level immune responses over time, considering contextual factors specific to our country, such as genetic specificities, co-morbidities (other existing health problems), organization of the supply and dispensation system, as well as the duration of the immunity conferred.”
Furthermore, the emergence of viral variants with mutations in the “S gene” (spike protein gene) highlights the need for ongoing characterization of vaccine-induced immunity. The study addresses this gap by providing the first SARS-CoV-2-related serological data from Morocco, offering insights into the prevalence of antibodies induced by infection and/or vaccination.
As of April 21 of last year, 23,423,963 individuals in Morocco have received their second dose of the COVID-19 vaccine, representing a vaccination coverage rate of approximately 65% of the population.
Additionally, 6,883,240 participants have received their third dose, and 60,739 individuals have been vaccinated with the fourth dose which marks Morocco as having the highest level of vaccination coverage among countries in Africa, according to the study.
