With all eyes on the rapid global spread of the novel coronavirus, health experts fear a drop in routine vaccinations could fuel other, potentially deadlier outbreaks of diseases like measles.
With nearly half of the world's population told to stay at home, many parents are having to postpone taking their children in for routine immunisations, while big vaccine drives have been halted, leaving many vulnerable to a range of infectuous diseases.
"Measles is probably number one in my worry list at the current time," Seth Berkley, who heads the Gavi Vaccine Alliance, told AFP in an interview.
He warned of the impact that an outbreak of measles or other diseases could have on health services already reeling from the COVID-19 pandemic, which has killed some 40,000 people and infected 800,000 worldwide in a matter of months.
"Routine immunisation is absolutely critical always, but is particularly critical at a time like this because if other outbreaks occur, they will overwhelm the health system," Berkley said.
He pointed out that during the Ebola outbreak in the Democratic Republic of Congo's North Kivu region, which has killed nearly 2,300 people since mid-2018, measles has proved more deadly.
"Everybody was focused on Ebola, but 2.5 times the number of people died in the country from measles than died from Ebola," he said.
Gavi provides vaccines against a wide range of diseases for the 60 percent of the world's children who live in developing countries.
While it may not be too big a deal to delay vaccines for some of those diseases for a few months, timely immunisation against the more contagious ones like measles is essential.
Already, the world is facing a resurgence of the once all-but-eradicated disease, which is a highly contagious, sometimes fatal viral infection.
Poorer countries are hit hardest. The vast majority of the more than 140,000 global measles deaths recorded by the World Health Organization in 2018 were in sub-Saharan Africa.
But a growing anti-vaccine movement has also helped spark measles outbreaks in many richer countries in recent years.
The anti-vax phenomenon has adherents across Western countries but especially in the United States, where it has been fuelled by the spread on social media of medically baseless claims, debunked 20 years ago, that the jab could cause autism.
Berkley pointed out that Europe has seen recent outbreaks in 47 out of 53 countries, warning that while the outbreaks had been small, if vaccination coverage falls, "these could be massive outbreaks".
He acknowledged that the physical distancing measures in place in many countries to halt a spread of the new coronavirus could also prevent broad spread of other infectuous diseases too.
"If there is less contact there is less likely to be an explosive spread," he said, while stressing that "measles is even more infectuous than COVID".
Meanwhile, Berkley said the pandemic might undermine the anti-vaccine movement.
He pointed out that one reason behind the hesitancy to immunise in wealthy countries was that "vaccines have been so successful that we don't see the diseases (they protect against) anymore."
"So it is easy to say: oh, these diseases aren't so severe, and we don't want to put non-organic things in our bodies, or we are worried about side-effects or whatever," he noted.
"I have a feeling that if there was a COVID vaccine right now, there might be more appetite to use it than has been the case for other vaccines."