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expert reaction to comments reportedly made yesterday by Dr Mike Ryan of the WHO suggesting increases in COVID-19 cases in Ireland has been mainly due to increased social mixing rather than the new variant

The World Health Organisation’s Dr Mike Ryan told reporters yesterday the increase in COVID-19 cases in Ireland was not due to the new variant, but due to increased social mixing and reduction of physical distancing.

 

Prof David Heymann, Professor of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, said:

“All coronaviruses can only transmit if behaviour is such that people don’t properly protect themselves and protect others (physical distancing and mask wearing respectively).  The virus has no impact on behaviour, but behaviour gives the virus the opportunity to transmit – and the new variant is hypothesised, with some data, to infect with a result of greater levels of virus in the nasal passages which therefore gives an opportunity to transmit more efficiently; or another hypothesis is that the spike protein mutations provide the capacity of the spike to adhere more easily to human cells.  Both remain hypotheses as far as I understand from meetings at WHO, and studies are being conducted that test these two hypotheses.”

 

Prof Paul Hunter, Professor in Medicine, The Norwich School of Medicine, University of East Anglia, said:

“I think Dr Ryan was wrong when he seemed to suggest that the recent surge in cases in Ireland was not linked to the new variant.

“The evidence is very clear in the UK that the new variant has been surging whilst other variants have been in decline.  Indeed, this new variant surged in the UK when we were in the November lockdown.  We also know that the English variant was indeed spreading in Ireland in December.

“Part of the problem seems to be that the Republic of Ireland are sequencing far fewer strains than the UK and given the time taken to get gene sequencing results there have been very few sequences posted from Ireland since mid-December https://nextstrain.org/ncov/global.  So although we cannot say for certain what proportion of the number of Irish infections in recent weeks were due to the new variant, it would be very unexpected if we ultimately decide that it did not make an important contribution to the Irish epidemic.”

 

Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, University of Leicester, said:

“Although several UK studies have suggested a 50-70% higher transmissibility for this new UK B.1.1.7 variant, at around the time of its peak emergence before Christmas 2020, there was the additional factor of people coming out of the UK November national lockdown into the less stringent Tiers – particularly with London emerging into Tier 2, then shortly afterwards into Tier 3 – both of which still allowed non-essential shops to open.

“This meant that Christmas shopping could continue until Tier 4 was implemented just before Christmas – which would have allowed massive virus seeding, including the new UK variant – before the one day Christmas Day amnesty where up to 3 households to meet under one roof for a day.

“This Christmas Day gathering, unfortunately, would be more than enough to further transmit the virus across multiple households from all over the country, when meeting in one house, in crowded, close contact, poorly ventilated conditions with no mask-wearing.

“This type of enhanced social contact founder effect could have seeded the UK variant virus across multiple households before and during Christmas which may be contributing to the current surge of cases in the UK.

“Even if the UK variant is more transmissible to some extent, it is difficult to exclude any earlier enhanced social contact contribution to this current spread – as even the most transmissible virus still needs to be in the vicinity of a susceptible host to spread.

“Once any founder effects arising from this enhanced social mixing had occurred, resulting in further spread of this new UK B.1.1.7 variant, then even a normal viral transmission rate (similar to that of other viral strains) will result in more of the UK variant being present in positive samples – similar to the earlier D614G variant that became globally distributed, but without a markedly increased transmissibility.

“However, that D614G variant occurred in Spring/Summer without the massive boost from a pre-Christmas shopping period that likely contributed to the massive spread of the UK B.1.1.7 variant that we are dealing with now.

“Also, the colder, darker winter season naturally sees people spending more time indoors, where it is more crowded and viral transmission is enhanced – as we see with other seasonal respiratory viruses each year.

“So the ‘enhanced’ transmissibility of the UK B.1.1.7 variant may be due to both seasonal social and environmental factors, as well as any possible intrinsic higher transmissibility conferred by the actual viral mutations themselves.”

 

 

e.g. media reports at https://www.irishtimes.com/news/health/covid-19-surge-due-to-increased-social-mixing-says-who-s-mike-ryan-1.4455748 and https://www.independent.ie/videos/dr-mike-ryan-irelands-covid-19-cases-due-to-socialising-not-variant-39960254.html

 

 

All our previous output on this subject can be seen at this weblink:

www.sciencemediacentre.org/tag/covid-19

 

 

Declared interests

None received.

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