Key Points

The COVID-19 pandemic began in Mayotte nearly a year ago with a relatively mild first wave around May 2020. Since then, viral circulation has never ceased on the territory, and sporadic surges in cases were recorded during the second half of the year, linked to school breaks, the emergence of large clusters, and several large-scale testing campaigns.

In late December 2020, the first signs suggesting an intensification of the epidemic were detected, with an increase in SARS-CoV-2 incidence and positivity rates across all age groups and municipalities on the island. At the same time, on December 18, the South African government reported the emergence of a variant designated 501Y.V2. Genetic sequencing indicates its presence in South Africa since November. Today, this variant accounts for the majority of cases in the country. It has been identified in 40 countries according to the WHO, including several of Mayotte’s neighbors such as the Union of the Comoros and Mozambique.

Since the beginning of the year, all epidemiological indicators point to a rapid and severe deterioration of the Covid-19 health situation in Mayotte. This concerning trend comes amid the presence of more transmissible variants. Over the past three weeks, the incidence rate (IR) has more than doubled. The positivity rate tripled between mid-December and late January, particularly among children aged 0–14 over the past two weeks (+43%), calling for special vigilance in the pediatric population, which no longer appears to be spared from infection.

Hospital indicators reflect the severity of this new wave of the epidemic. The pattern of admissions for severe cases at the CHM differs from the first wave: oxygen-dependent respiratory cases are on the rise, particularly in the emergency, medical, and intensive care units. After a 15-day period in late December with no COVID-19 admissions to intensive care, a resurgence of severe cases has been observed since the first week of January. The number of patients admitted to intensive care each week has been rising steadily and rapidly for the past three weeks (10 ICU admissions last week and already 7 patients admitted this week as of February 4). As long as the island continues its climb toward the epidemic peak, the CHM is expected to see a significant increase in admissions over the next ten to fifteen days.

To monitor new SARS-CoV-2 variants in Mayotte (particularly the 501Y.V2 variant) and better characterize them, a sequencing protocol is currently in effect, in collaboration with the Respiratory Virus Center in mainland France. To date, 295 samples have been sequenced, and the South African variant has been identified in 77 of them. One sample revealed the presence of the UK variant in a patient who had traveled with multiple stopovers. Given the difficulties with contact tracing and isolating cases in Mayotte, community transmission of the 501Y.V2 variant is likely.

Currently, uncertainties remain regarding the 501Y.V2 variant and the mutations it has accumulated. Questions arise regarding the immune response, the risks of reinfection, and the potential loss of vaccine efficacy. Further studies must be conducted to determine the genetic, immunological, clinical, and epidemiological characteristics of SARS-CoV-2 variants.