Research

Australia: Experts accuse federal government of ignoring science on airborne COVID spread

This week, news in the Australian media revealed that according to our won doctors the federal government’s refusal to seriously acknowledge that COVID-19 can spread through the air could put healthcare workers' lives at risk. They say it is out of step with scientific evidence.

Official public advice from the federal Health Department is that the coronavirus is spread by close contact between people, droplets from a cough or sneeze, or contamination on surfaces. It does not warn of airborne spread, and the department says there is little evidence this is a major route of transmission.

Readers of our journal will know that the scientific evidence of aerosol spread has been growing. In June, research based on models of transmission showed aerosol spray high risk, particularly indoors (SafetyNet 535). In July 239 scientists from 32 countries wrote an open letter urging WHO to change their advice regarding droplet size, saying “We ignore COVID-19 airborne spread indoors at our peril.”  (SafetyNet 540). And in September, a US expert warned that transmission of COVID-19 through an airborne aerosol is “stronger than that for any other pathway”, greatly increasing the preventive efforts required. (SafetyNet 548).

Both the US Centre for Disease Control and Prevention (CDC) and now the British government (SafetyNet 553) warn that airborne spread is more likely than surface contamination, and is most likely when an infected person has spent more than 30 minutes in an enclosed space.

Many Australian experts on viral transmission say there is now strong evidence the virus can spread by air. “There is overwhelming evidence of airborne spread,” said Professor Raina MacIntyre, head of the biosecurity research program at the Kirby Institute. Read more: The Age 

Airborne virus a ‘major’ transmission risk

There is ‘overwhelming evidence’ that inhalation of the coronavirus represents a major transmission route for Covid-19, scientists have warned. The warning from experts from six US universities contradicts a position promoted by the World Health Organisation (WHO), which has played down airborne risks and said transmission by larger droplets is the predominant mode of transmission.  However, the letter published in Science magazine, notes “aerosols containing infectious virus can also travel more than 2m and accumulate in poorly ventilated indoor air, leading to superspreading events.” The letters adds: “Individuals with Covid-19, many of whom have no symptoms, release thousands of virus-laden aerosols and far fewer droplets when breathing and talking. Thus, one is far more likely to inhale aerosols than be sprayed by a droplet, and so the balance of attention must be shifted to protecting against airborne transmission. In addition to existing mandates of mask-wearing, social distancing, and hygiene efforts, we urge public health officials to add clear guidance about the importance of moving activities outdoors, improving indoor air using ventilation and filtration, and improving protection for high risk workers.” 
Read more: Kimberly A. Prather, et al. Airborne transmission of SARS-CoV-2, Science, 5 October 2020. DOI: 10.1126/science.abf0521. COVID-19: epidemiology, virology and clinical features, PHE guidance, updated 30 September 2020. Source: Risks 969

Most with positive tests in England have no symptoms

Over three quarters of people in England testing positive for the coronavirus responsible for COVID-19 (SARS-CoV-2) had no symptoms on the day of the test, with another 10 per cent having none of the core symptoms, a study has found.

The researchers said the findings were important because asymptomatic individuals can be “silent” transmitters. Irene Petersen and Andrew Phillips from University College London (UCL) used data from the Office for National Statistics Coronavirus (COVID-19) Infection Survey pilot study. “In total, there were 36,061 individuals with a SARS-CoV-2 test between 26 April and 27 June 2020. Of these, 625 (1.7 per cent) reported symptoms on the day of the test. There were 115 (0.32 per cent) with a positive SARS-CoV-2 test result. Of the 115, there were 27 (23.5 per cent) who were symptomatic and 88 (76.5 per cent) who were asymptomatic on the day of the test.” The paper added “99 (86.1 per cent) did not report specific symptoms on the day of the test.”

The authors conclude “COVID-19 symptoms are poor markers of SARS-CoV-2. Thus, 76.5 per cent of this random sample who tested positive reported no symptoms, and 86.1 per cent reported none of those specific to COVID-19.” They concluded: “A more widespread testing programme is necessary to capture ‘silent’ transmission and potentially prevent and reduce future outbreaks.”

This research highlights why testing in areas where the virus has been detected is important, and also why it spreads so easily. 

Read more: Petersen I, Phillips A. Three quarters of people with SARS-CoV-2 infection are Asymptomatic: Analysis of English Household Survey Data, [Full text] Clinical Epidemiology, volume 12, pages 1039-1043, 2020. Covid: more than 80% of positive UK cases in study had no core symptoms The Guardian. Source: Risks 969 

 

 

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