WHO Experts Weigh in on Measles, Monkeypox and COVID Bivalent Vaccines
WHO’s SAGE: executive secretary Dr Joachim Hombach, chair Dr Alejandro Cravioto and WHO’s Dr Kate O’Brien.

Measles outbreaks are escalating in large parts of the world thanks to “backsliding” in national immunisation programmes during the COVID-19 pandemic, the World Health Organization’s (WHO) Strategic Advisory Group of Experts (SAGE) on immunization warned on Tuesday.

“There were 25 million children un- or under-vaccinated in 2021,” said Dr Kate O’Brien, WHO’s director of immunization, vaccines and biologicals, warning that many of these children were now at risk of measles, which is “one of the most infectious viruses with somewhere between 12 and 18 people being infected by one measles case.”

“We are seeing an escalating in measles outbreaks. They’re escalating in number, they’re escalating in the number of countries, and they’re escalating in the size of the outbreaks. And so we’re watching the fire coming towards and this … will result in a large number of deaths unless action is taken,” she warned.

“When a critical fraction of a country or community’s population is not immune, and measles is circulating, you’re going to get massive outbreaks,” she said, urging countries to launch catch-up campaigns.

SAGE executive secretary Dr Joachim Hombach warned that malnourished children faced a greater risk of severe measles, and this was a concern given the global rise of malnutrition.

All three vaccines for monkeypox 

SAGE chairperson Dr Alejandro Cravioto

SAGE also recommends the use of all three vaccines currently available to prevent monkeypox, namely the smallpox vaccine, ACAM2000, as well as Bavarian Nordic’s MVA-BN (JYNNEOS) and the Japanese-produced LC16.

“For healthy adults, any of the three currently available vaccines is appropriate,” according to SAGE chairperson Dr Alejandro Cravioto, which marks a change from WHO’s interim guidance that initially warned against the use of ACAM2000.

However, SAGE noted that “for individuals for whom replicating or minimally replicating vaccines are contra-indicated, non-replicating vaccines should be used”. 

It advises pre-exposure vaccination for high-risk groups –  gay, bisexual, or other men who have sex with men (MSM) with multiple sexual partners. 

“Others at risk include individuals with multiple casual sexual partners; sex workers; health workers at repeated risk of exposure; laboratory personnel working with orthopoxviruses; clinical laboratory and health care personnel performing diagnostic testing for monkeypox; and outbreak response staff,” said Cravioto.

SAGE also advises post-exposure vaccination (PEPV) for the close contacts of monkeypox cases​​, ideally within four days of first exposure. 

Lack of evidence about vaccine efficacy

Kate O’Brien, WHO’s director of immunization, vaccines and biologicals

However, SAGE conceded that there was little evidence about the impact of the various vaccines on monkeypox. 

“I want to remind people that we’re at the very beginning of understanding the data on the effectiveness of these vaccines, which have not until this point been deployed against monkeypox and especially in the context of the current outbreak,” said O’Brien.

“We do know that the MVA Bavarian Nordic vaccine is in constrained supply, and we’re also working with countries to understand what their demand is for these vaccines,” said O’Brien.

The WHO is working on “this constrained supply” with affected countries and manufacturers “to understand what the scaling of supply could be, and especially matching that supply up with the demand”, she added. 

“This also has to do with how the vaccines are deployed, as you know there are some countries that have chosen to deploy the vaccines using a fractional dose, which of course is dose-saving,” she added

“Our recommendations are really in the context of this outbreak to contribute to the end of the human-to-human transmission that’s occurring in countries that have not otherwise had monkeypox cases, as well at the same time, providing those same recommendations for countries that have monkeypox cases,” said O’Brien.

According to the latest WHO report on monkeypox, between 21 September and 5 October, 7147 new cases (11.6% increase in total cases) and three new deaths have been reported. 

Twenty-six countries reported an increase in cases, with the highest increase in Nigeria (44.4%). Overall, 39 countries have not reported new cases for over 21 days, the maximum incubation period of the disease. 

The WHO also launched its Monkeypox Strategic Preparedness, Readiness and Response Plan last week which outlines the priority actions needed to stop human transmission of monkeypox, minimize animal-to-human transmission of the virus, and protect vulnerable groups at risk of severe disease. 

COVID bivalent vaccines and Corbevax

SAGE also noted that it was too early for it to pronounce on the efficacy of bivalent COVID-19 booster vaccines, containing the mRNA of the original strain and that of the Omicron sub-lineages.

As a result, it recommended that booster vaccinations four to six months after the last dose, with either the bivalent or original vaccines, would “provide improved protection against currently circulating SARS-CoV-2”.  

It also reviewed the data of Corbevax (BECOV-2) the non-patented vaccine developed by researchers at the Texas Children’s Hospital that is currently being manufactured and used in India.

“SAGE will issue recommendations once the product is listed by WHO for emergency use (EUL),” it noted.

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