Researchers in the UK report that much of the potential beneficial impact of the November 2020 English National lockdown on the coronavirus disease 2019 (COVID-19) epidemic was likely undermined in many areas due to increased socializing in the days running up to its implementation.
They say that information leaked about the intended lockdown five days prior to its implementation led to increased socializing in areas that had been categorized as Tier 1 and tier 2 as part of the country’s three-tier system.
The three-tier system was introduced on October 14th as a more sub-regional approach to controlling the epidemic. While people living in the less socially restricted tiers 1 and 2 were allowed to mix in groups of six outdoors and attend pubs and restaurants that were serving food or drink, those in tier 3 faced much more stringent regulations. In tier 3, people were banned from socializing indoors, in private gardens, and in most outdoor settings, with hospitality venues only allowed to operate as restaurants.
Now, Paul Hunter and colleagues from the University of East Anglia report that in Tier 3 authorities, the epidemic was already on the decline prior to the November national lockdown and continued to decline following its implementation. However, among Tier 1 and 2 authorities, the number of infections spiked soon after it was leaked that a lockdown was likely and continued to increase for up to two weeks after the lockdown was implemented.
The researchers say that much of this increased infection rate was associated with the emergence of the new, more transmissible variant.
“From our analysis, it is doubtful that even a return to the November lockdown conditions would be sufficient to control the spread of the new variant,” they write.
A pre-print version of the paper is available on the medRxiv* server, while the article undergoes peer review.
New case number in by specimen date for England
*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
More about the three-tier system and national lockdown
On October 14th, the English government introduced a three-tier system as a sub-regional approach to controlling the COVID-19 epidemic. During the last two days of October, it was widely leaked that the government was going to implement a new national lockdown, and just three weeks after the tier system was introduced (November 5th), a national lockdown was imposed across all areas of England.
Rolling 7 day incidence by region and associated mean R values by region
Once the lockdown ended on December 2nd, regions across the country were again placed in different tiers, although most were moved one tier up from pre-lockdown tiers.
“However, the effectiveness of the tier system has been challenged by the emergence of a new variant of SARS-CoV-2 which appears to be much more infectious,” writes Hunter and colleagues.
What did the researchers do?
The researchers set out to determine what impact the November national lockdown had on controlling the COVID-19 epidemic in England.
All data on the numbers of daily numbers of new COVID-19 cases from October 14th to December 8th were downloaded from the English Department of Health and social care daily COVID dashboard.
For each local authority (local government area), the effective reproductive number (R-value) for preceding days was estimated by summing all reports of new infections for each day and the previous six days. This was then compared with the sum of new cases over the previous seven-days.
The team also estimated the epidemiology of the new variant strain that was identified in the autumn of 2020.
What did they find?
Overall, the R-value declined across all three tiers during the first two weeks of the October tier system. However, it started to surge across Tier 1 and 2 authorities after October 20th, reaching a peak on November 13th.
No such surge was observed in Tier 3 authorities, which instead saw a steady decline up to around November 25th. In tiers 1 and 2, a decline was also seen up to November 25th, by which point the R-value was around 0.7 across all three tiers.
However, the R-value then started to increase again, particularly across authorities that had previously been in Tiers 1 and 2.
To further investigate the early November and early December surges, the team investigated data on age-specific incidence.
In almost all regions, the early November surge in incidence was most obvious among the 20 to 24 and 25 to 29 age groups. However, the incidence dropped across these age groups following lockdown.
Given that this surge during early lockdown did not occur in Tier 3, and was most obvious among those aged 20 to 29, a link to increased socializing in the days before lockdown is plausible, says Hunter and the team.
What about the new variant?
The researchers say the most striking observation was that across London, the South East and East of England, where incidence increased towards the end of lockdown, significant increases were observed among the 10 to 14 and 15 to 19 age groups.
The analysis showed that from mid-lockdown in November to the first week in December, the R-value for most viral variants declined, while it dramatically increased for the new variant.
The estimated R-value for London, the East of England, and the southeast regions for the novel variant was 1.3, 1.3, and 1.1, respectively, compared with 0.91, 0.92, and 0.97 for all other strains combined.
The team concludes that in Tiers 1 and 2, much of the beneficial impact of the national lockdown was probably lost due to leaked information about its likely implementation leading to increased socializing in these areas before it even began.
“We further conclude that given that the new variant is estimated to have an R-value of between 0.39 and 0.93 greater than previous variants, any lockdown as strict as the November one would be insufficient to reverse the increase in infections by itself,” writes Hunter and colleagues.
*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
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