[YAOUNDE] The insufficient doses of vaccine and the shortage of stocks of diphtheria antitoxins (products which neutralize the toxin, a poison secreted by the bacteria responsible for the disease) have not made it possible to provide an effective response to the diphtheria epidemic. which has already caused more than 1,300 deaths in Nigeria, Niger and Guinea.
According to Julien Potet, senior advisor in charge of neglected tropical diseases (NTDs) at Médecins Sans Frontières (MSF), there were “unfortunately” no large relief stocks for vaccines and antitoxins before the start of the epidemic.
“Before the epidemic, there was no program, to my knowledge, allowing certain doses of vaccine to be switched to catch-up vaccination. The vaccines available in the countries were exclusively reserved for routine vaccination under the Expanded Program on Immunization,” he says.
“Producers of vaccines and toxoids want to have guarantees that their investments to increase their production capacities will result in an increase in orders in the long term, otherwise the investment is not worth it”
Julien Potet, MSF
On the other hand, MSF and the World Health Organization (WHO) had an emergency stock of antitoxins in May 2023. “Unfortunately, this emergency stock was very insufficient in size,” regrets Julien Potet who spoke on April 29 during an online press conference organized by MSF on this epidemic.
According to the explanations of this expert, the shortage of diphtheria antitoxin is located in a particular context. This biotherapeutic drug is produced from horse plasma and there are today three approved producers, only two of which are capable of producing large quantities.
However, he says, these producers are reluctant to invest in new horses just to produce more doses for one or two years, while the epidemic lasts.
Thus, notes Julien Potet, “producers want to have guarantees that their investments to increase their production capacities will result in an increase in orders in the long term, otherwise the investment in new horses is not worth it, according to them” .
On the other hand, the situation “is a little better” for vaccines with no less than five producers prequalified for the vaccine; even if the latter operate almost in a just-in-time manner to serve the routine vaccination market.
Low vaccination coverage
And yet, the current diphtheria epidemic is due to low vaccination coverage, says Djeneba Thiam, biostatistician and head of epidemiological surveillance in West and Central Africa at the MSF office in Dakar (Senegal). “Only 24% of confirmed cases had received two doses of vaccine, which is very low,” she indicates.
“It was known that the coverage rate of basic diphtheria vaccination, that is to say the fact that children received at least three doses of vaccine, was very low,” adds Julien Potet.
“Not only that, the data put forward by the ministries of Health in Nigeria, Niger or Guinea had highlighted numerous areas with coverage rates lower than 40% for several years,” laments the latter.
Furthermore, he said, independent serological studies had confirmed low population-wide protection. “This kind of data should quickly prompt the launch of a vaccination catch-up campaign even before the first signs of an epidemic appear. Unfortunately, this could not take place,” regrets the MSF expert.
Consequences: 79% of cases and 71% of deaths were recorded in Nigeria. In detail, 35,324 suspected cases, more than 17,000 confirmed cases and 923 deaths have been reported in this country since the start of the epidemic in May 2022, specifies Djeneba Thiam.
In Niger, sporadic cases appeared in 2021, followed by an outbreak since 2022. Between 2023 and the first 15 weeks of this year, 4,875 suspected cases were reported for 296 deaths. As for Guinea, explains Djeneba Thiam, 2,240 suspected cases and 78 deaths were recorded in 2023 and 2,709 others already in 2024, including 16 deaths.
Emergency stocks
Cameroon, a country which shares more than 1000 km of border with Nigeria, is not really affected by this epidemic at the moment. Jean Taguebue, pediatrician and infectious disease specialist on duty at the Mother and Child Center of the Chantal Biya Foundation in Yaoundé, has an explanation…
He first recalls that in the past, the tetanus vaccination administered to pregnant women only contained the tetanus vaccine.
However, “almost ten years ago, we proposed adding to this vaccination a small dose of anti-diphtheria vaccine to protect pregnant women against both tetanus and diphtheria at the same time as they were giving them their booster shots. vaccination to protect the newborn. This has been done,” says the infectious disease specialist.
“When diphtheria meets a lady who has been vaccinated and who has given birth in recent years, she will not transmit the disease. It’s a little protection. I don’t think all African countries have done it…”, maintains Jean Taguebue.
MSF is therefore calling on States to implement booster vaccination against tetanus and diphtheria, as well as to constitute during periods inter-epidemic a real emergency stock of vaccines and antitoxins. Drawing inspiration from emergency stocks of vaccines that exist against cholera, yellow fever or Ebola.
The organization finally recommends the creation of emergency funds to help countries deal with epidemics, such as diphtheria.
