WHO official reveals coronavirus spread by asymptomatic people ‘appears to be rare’
A health official from the World Health Organization (WHO) has claimed the spread of COVID-19 by asymptomatic individuals “appears to be rare” but can still happen. WHO’s coronavirus response team have yet to find significant secondary transmission of the novel coronavirus from asymptomatic cases, even after looking at data from countries who are currently doing detailed contact tracing.
Maria Van Kerkhove, the team’s technical lead, explained how the novel coronavirus, a respiratory pathogen, spreads through droplets, which can be released when someone coughs or sneezes. “If we actually followed all of the symptomatic cases, isolated those cases, followed the contacts and quarantined those cases, we would drastically reduce transmission.”
Van Kerkhove also said that many asymptomatic cases of COVID-19 often turn out to be cases of mild disease. “They’re not quite COVID-19 symptoms, meaning they may not have developed fever yet, they may not have had a significant cough, or they may not have shortness of breath – but while some may have mild disease, we do know that there can be people who are truly asymptomatic.”
Following this, Dr. Manisha Juthani, an infectious diseases specialist and associate professor of medicine and epidemiology at Yale School of Medicine in Connecticut, US, revealed that people with mild or atypical symptoms could be pre-symptomatic. Pre-symptomatic refers to the early stages of an illness, before symptoms have developed, whereas asymptomatic may refer to having no symptoms throughout the course of an infection.
In addition, the US Centers for Disease Control and Prevention (CDC) estimated that almost 40% of coronavirus transmission could occur before people feel sick. Juthani noted that such patients weren’t asymptomatic, but were rather “spreading disease before becoming symptomatic.”
“This suggests that if we quarantine and contact trace symptomatic people, we can make a significant dent in the pandemic,” Juthani added.
Having atypical or very mild symptoms could also mean that someone has what is known as a paucisymptomatic infection, according to Babak Javid, a principal investigator at Tsinghua University School of Medicine in Beijing, China. Distinct from asymptomatic or pre-symptomatic infections, studies have found that paucisymptomatic transmission can occur even before or on the day symptoms first appear.
Javid emphasised, “Studies would suggest that being well does not necessarily mean one cannot transmit SARS-CoV-2 – this has important implications for the track/trace/isolate measures being instituted in many countries at this time.”
In other news, WHO is urging New Zealand to further develop its contact tracing systems, in case of a second coronavirus outbreak. The country has successfully avoided the brunt of the economic and public health effects of the coronavirus pandemic, so far.
WHO head of planning for the Western Pacific region, Dr. Matthew Griffith has compared New Zealand to South Korea and Japan. Both Asian nations are through the worst of their outbreaks but are still seeing new clusters pop up as they reopen. “What New Zealand can learn from countries like South Korea and Japan is that […] it’s not yet time to be complacent,” Griffith said.
New Zealand has not reported a new case of COVID-19 in over two weeks; there are no active cases either.
