New research suggests SARS-CoV-2, the coronavirus that causes COVID-19, may have been circulating outside China as early as mid-2019.
A month after the detection of COVID-19 in Wuhan on 8 December 2019, Europe’s first COVID-19 patients were reported in France: one in Bordeaux and two in Paris; all three had come from China. A week later on 31 January 2020, Italy confirmed its first two cases in Rome, followed on 21 February 2020 by both the country’s first major cluster in Codogno in Lombardy and initial deaths.
The suggestion of sporadic human infections before the Wuhan outbreak was initially raised in a joint study by China and the World Health Organisation (WHO) in March 2021; and in June 2021 UK researchers from the University of Kent estimated SARS-CoV-2 emerged in China on 17 November 2019 and had spread globally by January 2020.
Also in Europe, Italian researchers conducting measles and rubella surveillance in Lombardy, focusing on measles-like symptomology in 2018-2019, took 435 samples from 156 people and analysed them for the presence of SARS-CoV-2. Their study, published recently in The Lancet, found genetic material belonging to the virus in 13 samples – 11 from the pre-pandemic period, with the earliest on 12 September 2019, leading them to believe infections emerged between late June-August 2019. However, they found no evidence of infection in 281 samples collected between August 2018-July 2019, ruling out earlier virus circulation.
Meanwhile, scientists at Italy’s University of Siena, whose research was published in the journals Tumori and (after retesting samples) MedxRiv, analysed blood samples from 956 healthy volunteers during a lung cancer screening trial in October 2019 and found more than 100 had developed coronavirus-linked immunoglobulin M antibodies, immunoglobulin G antibodies or both – leading them to believe the volunteers had recently contracted SARS-CoV-2.
Again in Milan, on 10 November 2019 a 25-year-old female patient presented to her dermatologist with a plaque-like skin rash; a skin biopsy detected SARSCoV- 2 molecules in the sample.
Also in Italy, environmental monitoring of sewage in three cities between October 2019-February 2020 revealed the presence of SARS-CoV-2 RNA in 15 samples from Milan and Turin – the earliest on 18 December 2019.
Researchers from the University of Milan have also investigated the case of a boy who had a measles-like rash in December 2019; they analysed swabs from 39 people, including the boy, taken between September 2019-February 2020 – the only SARS-CoV-2 positive result was from the child, leading them to suggest SARS-CoV-2 could have been circulating for about three months before the first identified case in Italy.
In France on 27 December 2019 a 43-year-old man from Bobigny, who had not travelled abroad, received treatment at a hospital near Paris for a dry cough, difficulty breathing and fever; he was suspected of having pneumonia, but when his doctor retested the swab in May 2020, it came back SARS-CoV-2 positive – triggering discussions about earlier circulation in France.
US virologist Dr Semih Tareen told medicalnewstoday.com: ‘It’s not surprising there were cases as early as November 2019 outside Wuhan. This doesn’t mean they originated in Italy or France. The papers aren’t claiming that.
It simply says that…it is possible the earliest cases started in November or earlier, and then came over to Italy, most likely through international travel.’ Professor William Schaffner from Vanderbilt University agreed it was quite likely COVID-19 was circulating undetected in Wuhan and had already spread to other countries before doctors first diagnosed it: ‘There is much transmission of COVID-19 that is without any symptoms or only mild symptoms. This permits wide transmission that can go undetected for a long time. Thus these retrospective studies likely are correct in determining the virus was circulating in Europe considerably earlier than first thought.’
