The grim pall of the COVID-19 pandemic sets 2020 as a notorious year in the history of human disease.
But this dark chapter contained some surprises for which we can also be grateful. In a new study, researchers found that a predicted outbreak of a mysterious crippling disease in 2020 was off track – and in a weird way, we actually have the coronavirus to thank for it.
The condition in question is called acute flaccid myelitis (AFM). This polio-like neurological disease mainly affects children and causes muscle weakness and, in some cases, permanent paralysis and even death.
For decades, cases of AFM were very rare, but larger outbreaks have occurred in the US and elsewhere in recent years, appearing to recur every two years.
A number of previous research has linked AFM to a rare virus called enterovirus D68 (EV-D68), and while it is not yet known how the virus displays the symptoms of AFM disease, converging outbreaks of the pair have led researchers to believe that they are. almost certainly related.
In the new study, a team led by Princeton University’s first author and modeler of infectious diseases Sang Woo Park tracked patterns of EV-D68 cases between 2014 and 2019, with the virus causing significant flare-ups in even years – 2014, 2016. and 2018 – believed to be due to climate-related factors.
The data suggested that 2020 would take another hit.
“We predicted that a major outbreak of EV-D68, and thus an AFM outbreak, would still have been possible in 2020 under normal epidemiological conditions,” the researchers explain in their study.
Of course, as the world struggled to witness, the epidemiological conditions of 2020 were anything but common, and the expected EV-D68 and AFM combo hit never materialized.
In the US – a country with significantly more cases of COVID-19 than any other – the combined effects of physical distance, quarantine and isolation policies, and economic and civil shutdown seemed to not only reduce the spread of SARS-CoV-2, but EV -D68 too.
“Our preliminary analysis indicates that the COVID-19 pandemic response likely affected the dynamics of a 2020 EV-D68 outbreak,” the authors write.
According to the researchers, there were 153 cases of AFM in 2016 and 238 cases in 2018, but only 31 cases in 2020.
In light of all that the US has been through in recent times, these are some numbers to feel good about.
Still, there’s no time for complacency – especially since the EV-D68’s unplanned gap year may have left a greater void in viral immunity at the population level.
“Based on the low number [predicted] EV-D68 cases in 2019, we would expect the number of susceptible individuals to increase, increasing the likelihood of a major outbreak, “the team said.
“If social distance prevents the outbreak, the susceptible pool could widen even further.”
The findings are reported in Science translational medicine