<div>High SARS-CoV-2 IgG seroprevalence among pregnant Cameroun women 14
months after the beginning of the pandemic</div><div>Jean-Michel Mansuy (1), Martial Tsague Kenfack (2), Suzanne Burel (1),
Candice Pollani (1), Marlise Bidzogo Lebobo (2), Célestin Ondobo Ekaé
(2), Antoine Berry (3,4), Jacques Izopet (1,4)</div><div>1 – Virology Department, Centre Hospitalier Universitaire (CHU) de
Toulouse, 31059 Toulouse, France</div><div>2 - Health Care Center of the CASS, Yaoundé, Cameroon</div><div>3 – Parasitology – Mycology department Centre Hospitalier
Universitaire (CHU) de Toulouse, 31059 Toulouse, France</div><div>4 – INSERM UMR1291 – CNRS UMR5051, Toulouse Institute for Infectious
and Inflammatory Diseases (INFINITy), 31300 Toulouse, France</div><div>The two years following the COVID-19 pandemic triggered by the
appearance of severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) in Wuhan (China) have seen the virus evolve, producing
variants that have driven successive waves of infection. The total
number of COVID-19 cases worldwide is now close to 430,000,000, with
over 5,900,000 deaths.</div><div>There were very few reported cases of COVID-19 on the African continent
during the early stages of the pandemic, especially in sub-Saharan
Africa. But modelling studies indicated that some African countries were
highly vulnerable and not well equipped to respond to an outbreak<sup>1</sup>. The World Health Organisation (WHO) and its
partners launched the COVID-19 Access Tool Accelerator (ACT) in April
2020 to address this inequality by developing effective tools to manage
COVID-19 in middle-and-low income countries (MLIC).</div><div>However, Africa seemed to remain more resistant to the coronavirus than
other continents, perhaps because of the warm climate, young population,
or the immune history of its peoples. The dynamics of the disease in
Africa surprised the world, thwarting many predictions, despite the lack
of medical facilities, the poor adherence to or impossibility of social
distancing and overcrowded cities. It soon became clear that this
under-reporting was probably due to a lack of screening, and that
SARS-CoV-2 was emerging in many African countries just as it was in the
rest of the world. Nevertheless, clinical reports of cases of the
disease were scarce, as were unexplained deaths that could be attributed
to COVID-19.</div><div>Two years into the pandemic the global epidemiological map of Africa
does not seem to have changed, except for northern African countries
(<i>https://coronavirus.jhu.edu/map.html</i>).
The current published number of COVID-19 cases/10<sup>6</sup>inhabitants varies from 3.10<sup>-3</sup> in the Central African
Democratic Republic to 4.3.10<sup>-4</sup> in Chad, and
4.10<sup>-3</sup> in Cameroon. The comparable indicators in
developed countries are: 0.3 in France, 0.23 in the USA, 0.19 in Italy,
and 0.08 in Brazil (all x 10<sup>-3</sup>). The number of
reported cases per inhabitant is almost 100 times smaller in
sub-Saharian Africa than in France, Italy or the US.</div><div>We estimated the prevalence of SARS-CoV-2 in Cameroon by testing for
specific antibodies against the virus (SARS-CoV-2 IgG II Quant Alinity i
Abbott) <sup>2</sup>. We collected serum samples from 292
pregnant women being cared for on a maternity ward (Health Care Center,
Centre d’Animation Sociale et Sanitaire) in Yaoundé. This maternity
hospital performs about 4500 deliveries per year. The women were 16 to
47 years old (mean: 26.8; median: 26). Three quarters of them (225;
77%) tested positive (6 to 1081 Binding Arbitrary Units per ml)
although none of them had been vaccinated against COVID;their antibody
titers were not correlated with their age.</div><div>The high seroprevalence in unvaccinated women mirrors the upsurge in
COVID-19 cases, most of which are asymptomatic or paucisymptomatic. This
suggests that the virus was already actively circulating in this area by
the first half of 2021. The first cases of COVID-19 in Cameroon were
reported in early March 2020 (Ministry of Public Health Cameroon: COVID,
2021. Available at: http://COVID-19.minsante.cm/) and the virus
had spread so well that prevalence studies showed that the
anti-SARS-CoV-2 IgG seroprevalence was 24% in June-August 2020, just 8
months after the emergence of the virus. The figures are the same as
those reported for a neighboring country in October/November, 2020<sup>3</sup> and in the general populations of other African
countries <sup>4</sup>, after tests on healthy blood donors<sup>5</sup>, health workers exposed to COVID-19 patients<sup>6</sup>. Thus Africa was not spared by the pandemic and the
current under-reporting of cases is due to a lack of screening, little
or no increase in clinical cases suggesting COVID-19, and little or no
increase in reports of unexplained deaths.</div><div>The two-dose vaccination rate does not exceed 11% in many African
countries, but the question of whether or not to immunise African people
against covid 19 remains unanswered as long as a universal vaccine
against SARS CoV 2 is unavailable <sup>7</sup>. Should what has
not been done since the beginning of the pandemic still be attempted in
view of the the active circulation of the virus, as indicated by the low
overall COVID-19 morbidity and mortality, and the high seroprevalence?</div><div>We believe that vaccination policies should be redefined, given the
delay and the evidence of active virus propagation in Africa. The target
populations for vaccination could be more precisely defined, based on
regular seroprevalence surveys of the general population. It is no
longer a question of mass vaccination of a population that is already
naturally immune to SARS-CoV-2, but rather of targeting at-risk groups
such as the elderly, people suffering from co-morbidities, and
healthcare workers. Last, the really urgent need is to resume the
Expanded Programme on Immunization as soon as possible, because the
COVID-19 pandemic has dramatically worsened the implementation of
« classical » immunisation campaigns in many countries<sup>8</sup>. This is where human and financial resources should
now be directed.</div><div>1. Gilbert M, Pullano G, Pinotti F, et al. Preparedness and
vulnerability of African countries against importations of COVID-19: a
modelling study. The Lancet 2020;395:871-877.</div><div>2. Chapuy-Regaud S, Miédougé M, Abravanel F, et al. Evaluation of Three
Quantitative Anti-SARS-CoV-2 Antibody Immunoassays. Microbiol Spectr
2021;9:e0137621.</div><div>3. Nkuba AN, Makiala SM, Guichet E, et al. High prevalence of
anti-SARS-CoV-2 antibodies after the first wave of COVID-19 in Kinshasa,
Democratic Republic of the Congo: results of a cross-sectional
household-based survey. Clin Infect Dis Off Publ Infect Dis Soc Am June
2021:ciab515.</div><div>4. Fryatt A, Simms V, Bandason T, et al. Community SARS-CoV-2
seroprevalence before and after the second wave of SARS-CoV-2 infection
in Harare, Zimbabwe. EClinicalMedicine 2021;41:101172.</div><div>5. Mandolo J, Msefula J, Henrion MYR, et al. SARS-CoV-2 exposure in
Malawian blood donors: an analysis of seroprevalence and variant
dynamics between January 2020 and July 2021. BMC Med 2021;19:303.</div><div>6. Somboro AM, Cissoko Y, Camara I, et al. High SARS-CoV-2
Seroprevalence among Healthcare Workers in Bamako, Mali. Viruses
2022;14:102.</div><div>7. Morens DM, Taubenberger JK, Fauci AS. Universal Coronavirus Vaccines
— An Urgent Need. N Engl J Med 2022;386:297-299.</div><div>8. Shet A, Carr K, Danovaro-Holliday MC, et al. Impact of the SARS-CoV-2
pandemic on routine immunisation services: evidence of disruption and
recovery from 170 countries and territories. Lancet Glob Health
2022;10:e186-e194.</div><div>CONFLICT OF INTEREST</div><div>none of the authors declare any conflict of interest</div><div>ACKNOWLEDGEMENT</div><div>The English text was edited by Dr Owen Parkes.</div>