Harvard did a comparison study between individuals infected with B.1.1.7🇬🇧 variant and the original virus variant.
Their aim was to try and determine why the virus was more transmissible (why on average a person infected with B.1.1.7🇬🇧 infects more people than the original variant. They looked to see whether it was connected with individuals releasing larger quantities of Viral particles or whether it was due to another factor.
The scientists estimated the time from first detectable virus in individuals to peak viral concentration (proliferation time) and then the time from peak viral concentration to initial return to the limit of detection (clearance time).
For individuals infected with B.1.1.7 🇬🇧, the average duration of the proliferation phase was 5.3 days with the average duration of the clearance phase was 8.0 days and the average overall duration of infection (proliferation plus clearance) was 13.3 days. This compared to a average proliferation phase of 2.0 days, an average clearance phase of 6.2 days and average overall duration of infection (proliferation plus clearance) of 8.2 days for the original 🇨🇳 variant.
The variant of the virus an individual was infected with did not have a significant effect on peak viral concentrations, which may indicate individuals are releasing similar quantities of virus regardless of the virus variant they are infected with. Put together this data provides evidence that B.1.1.7’s🇬🇧 increased transmissibility is due to it resulting in longer infections. As we know many people who contract COVID don’t isolate (this is often due to asymptomatic infection). If these individuals are infectious for a longer period of time they will make more contacts with other people, increasing the likelihood of them infecting more people.
This could be potentially good news for schools, shops and hospitality venues as it could mean that individuals infected with B.1.1.7🇬🇧 are not any more likely to transmit the virus when they come into contact with others. This would mean that measures put in place to mitigate spread prior to the emergence of B.1.1.7🇬🇧 would be just as effective. This would mean that we would not necessarily need to increase mitigation measures (e.g. we would not need to further reduce the number of people inside the building or invest in expensive and complex Ventilation systems).
The most effective way to target B.1.1.7🇬🇧 would be to step up Regular mass testing and increase the length of the subsequent isolation period. This would help to significantly reduce the time infectious individuals remain active within the community. If we could do this effectively it would reduce the average number of people infected by someone carrying B.1.1.7🇬🇧 to comparable levels to we saw with the original variant.
It is important to point out that this was only a small scale scale study based on 64 infected individuals, of which 7 were infected with B.1.1.7🇬🇧 The 64 infected individuals came from a large group of regularly tested individuals who were part of a professional sports league (NBA). This group included team staff, 148 players, arena staff, and other vendors (e.g., transportation, facilities maintenance, and food 149 preparation).