Zika virus no longer represents a public health emergency, the World Health Organisation announced on Friday. On the face of it, this sounds like good news. But this is not a downgrading of the threat of the virus – if anything, it’s an upgrading, says Christian Lindmeier of the WHO.
The emergency status was used when little was known about Zika virus, and an urgent response was required from funders and researchers to learn more. “Today, we are in a very different situation,” Peter Salama, head of the WHO’s health emergencies programme, told a press briefing on Tuesday. Now that we know that Zika causes brain damage in fetuses and newborns, and that it is spreading, we need a long term approach. “It’s critical that we recognise that Zika virus will continue to spread,” he says. “And we need to continue to be able to respond.”
From now on, the WHO’s fight against Zika will be referred to as “a medium-to-long term programme of work”. This means that research, diagnostics and treatment projects won’t be able to get money from emergency funders. But these donors tend to only fund projects lasting around 6 to 12 months. The pressing questions surrounding Zika will take years of research to answer, says Salama. He hopes that funding will start to come from other, more sustainable donors. “In many ways, this is actually an acknowledgment that the programme needs to escalate into a longer term programme of work,” he says.
Some of the most burning questions surround the history of the virus itself. It is not clear if different strains of the virus may have different effects, for instance, or whether there are other factors that make an infection more or less dangerous for a pregnant woman. It is also unclear whether people who are infected with Zika – or other, similar viruses – might be somehow protected from future infections.
We still don’t even know how many cases of Zika infection – and microcephaly in babies – there have actually been. For a start, 80 per cent of people infected with the virus don’t show any symptoms. Around 2,100 cases of microcephaly in babies have been linked to Zika so far, but 3,000 more are currently under investigation. And babies that appear healthy at birth can develop microcephaly later on, and experience other problems in brain development. We’re seeing that that definition of brain damage associated with Zika is expanding, says Salama, “so we may need to update whatever figure we give you today in terms of the risk.”
Janet Daly at the University of Nottingham in the UK, agrees with the reclassification. She hopes that the change will mean that funding will be more equally spread among other infectious diseases. “The way in which funding was pumped into [Zika virus research] initially, even by countries that weren’t affected, was great,” she says. “But a lot of people said that diseases like dengue have been a problem for years, and perhaps the money should be more equally allocated,” she says.
The WHO is also prioritising the hunt for a vaccine – one that can protect women of childbearing age, in particular. At the moment, there are around 30 potential candidates, but only a few have entered the earliest stages of clinical trials. “In all likelihood we are still a long way off having a commercially viable Zika vaccine,” says Salama.
“With all viral diseases, vaccines are the ultimate goal,” agrees Daly. But vaccines are never 100 per cent effective, and can mask the signs of disease, she says. It is also difficult to tell from a blood test whether someone has had an infection or a vaccination – making it harder to track a virus’s spread. And a vaccine for one strain of a virus can make infections with other strains of the same virus worse. “It’s really complicated,” she says.
In the meantime, the WHO will seek out long-term funding to make progress. “In summary, Zika virus is here to stay,” says Salama.