Latest COVID-19 science updates: no-symptom virus spread, airborne particles, and the virus’ impact on cancer deaths

Each week, Channel 4 News will provide a summary of key research papers, studies or developments from the world of COVID-19 science.

Study suggesting coronavirus crisis could cause thousands of extra cancer patient deaths (published 29/04/20)

Preliminary results of a UK study suggest that the coronavirus crisis could cause thousands of extra deaths of cancer patients.

The study follows a number of anecdotal concerns raised by healthcare workers about the diversion of NHS attention away from cancer care while it focuses on coronavirus.

The model-based study, led by researchers at University College London (UCL), is the first to estimate how many extra cancer deaths, known as excess mortality, might occur during the pandemic.

It hasn’t been peer reviewed yet, however, and experts commenting on the findings were cautious about the conclusions.

To create the models, the authors used real world figures on reductions in chemotherapy appointments, which they found have fallen by 45-66 percent, and reductions in urgent referrals for cancer diagnosis, down by 70-89 percent.

Experts commenting on the findings acknowledged that these are indeed large and concerning, but pointed out that other parts of the author’s models use assumptions on figures we do not yet have data on.

For example, the study presented a headline figure of a potential 6,270 additional deaths this year for newly diagnosed cancer patients.

But adjusting those assumptions gave excess deaths figures ranging from hundreds to tens of thousands.

Professor Kevin McConway, Emeritus Professor of Applied Statistics at The Open University, said: “It’s well known that there have been considerable changes in the provision of health care for many conditions, including cancers, as a result of all the measures to deal with the COVID-19 crisis,”

“It seems inevitable that there will be increased deaths in cancer patients, if they are infected with the virus, or because of changes in the health services available to them, and quite possibly also from socio-economic effects of the responses to the crisis.”

Broadly experts agree there will be excess mortality for cancer patients – but reiterated that the findings of this study need thorough reviewing by the science community to confidently establish how many.

The study authors concluded: “To better inform prioritization of cancer care and guide policy change, there is an urgent need for weekly data on cause-specific excess mortality, cancer diagnosis and treatment provision and better intelligence on the use of effective treatments for comorbidities.”

Study suggesting that coronavirus genetic material can persist in the air (published 27/04/2020)

A study has been published in Nature which found coronavirus RNA, a type of genetic material, was detectable in the air of hospitals in China.

The study authors proposed that this could be evidence of airborne transmission of the virus, which goes beyond the established evidence of large droplet transmission.

But they highlighted that their findings were of airborne genetic material only, not the functional virus itself – so said that more research is needed.

The study looked at the amount of coronavirus RNA in aerosols, tiny particles which float in the air, in hospitals treating coronavirus patients in China.

It found that viral RNA was most concentrated in patient toilets, but was very low in ventilated rooms and undetectable in all public spaces, excluding two very crowded areas.

The study authors said: “Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concentration of SARS-CoV-2 RNA in aerosols.”

Professor Lawrence Young from the University of Warwick said that the study importantly reiterated the need for protective equipment to be worn by medical staff, but said it was too early to conclude that the virus is readily transmitted through the air.

He said: “Detecting the virus genetic material (RNA) with a very sensitive test (RT-PCR) is not the same as detecting infectious virus. Dead or degraded virus would still be detected with this technique.

In fact, this method is so sensitive that there needs to be stringent control measures to prevent sample cross-contamination. The sampling of aerosols is subject to enormous variation and the small sample size in this study also means that the data needs to be interpreted with caution.”

Study which found presymptomatic coronavirus transmission in US care home (published 24/04/20)

A study published in the New England Journal of Medicine has found that more than half of residents in a US care home had no symptoms when they tested positive for coronavirus.

The study authors said that this reinforces previous evidence that coronavirus is readily spread by people with no symptoms, and may be a key factor in why the virus spreads so quickly in care homes.

“Infection-control strategies focused solely on symptomatic residents were not sufficient to prevent transmission after SARS-CoV-2 introduction into this facility,” the authors concluded.

The research reported that of 89 residents in the US care home, 64 percent gave positive results for coronavirus at the point of testing, and over half of these had no symptoms.

Yet half of those residents without symptoms went on to develop symptoms later, highlighting the difficulty of determining figures for people who are truly asymptomatic or merely presymptomatic at the point of testing.

The study also found that the amount of virus, or the viral load, found in residents who tested positive were the same in those with and without symptoms.

Over a quarter of the residents who tested positive for the virus died.

Both the study authors and other experts commenting on the finding concluded that disease control measures which only focus on symptomatic patients are not enough.

This may extend to wearing face masks by everyone in public as it’s now clear that the virus is spread between people with no symptoms, they said.

Last week’s update can be found here.