3. Results: Contacts by attitude: Page 11: One would not expect household size to change due to Covid, so it would be useful to compare polymod data within household contacts with these results to measure how well the studies match each other. Reading the manuscript, and given the growing scientific evidence of the difference in the contribution of internal and external contacts to SARS-Cov2 transmission, it is quite surprising to see no indication of internal and external contacts in the results. If you have recorded this information, I suggest you discuss it in the newspaper. Otherwise, I would call it a fairly significant limitation of the study and important data to be collected in future studies. Thank you for submitting your manuscript entitled “CoMix: Changes in social contacts as measured by the contact survey during the COVID-19 pandemic in England between March 2020 and March 2021” for review by PLOS Medicine. · Ask people who test positive for coronavirus and their close contacts to self-isolate. Strict restrictions remained in place during the Christmas holidays (for a large part of the population) and during lockdown 3. However, as early childhood education facilities remained open during lockdown 3, higher contact rates between <4 year olds were reported (Figure S6). An increase in school-to-age contact and a slight increase in adult-to-adult contact was observed during school reopening periods during lockdowns 2 and 3 (Figure S6).

This resulted in a much larger OR than in other lockdown periods, for example, during lockdown we estimated that 2 CRs were 2.42 (95% CI 2.31 to 2.53) and 1.60 (95% CI 1.54 to 1.66) times higher than lockdown 1, for age-equal and COVID-like transmissibility. All currently closed venues, including nightclubs, will be allowed to reopen, and there will be no legal requirement for table service in hotel environments. The results are fairly presented and accurately interpreted, and the main limitations of the study were discussed in depth in the discussion section. England`s response to COVID-19 has shifted from a national lockdown to a local response. In response to the increase in cases, these were supplemented by national restrictions on contact (rule of six), then closing at 10pm for bars and restaurants, and encouraging working from home. This was quickly followed by a 3-step system with different restrictions in different locations. As cases continued to rise, a second national lockdown was imposed. We used a national survey to quantify the impact of these restrictions on epidemiologically relevant contacts. Discussion 22: Line 504-506: Please revise the wording here to avoid causal implications (e.g., use of the word determinant): “Survey results suggest that government action has been an important factor in the average number of social contacts, with contact rates decreasing significantly during each lockdown. But that wasn`t the only determinant.

The panels were updated with a completely new sample in August 2020 after the end of the originally planned study period, and there was high participant turnover in January 2021 when participants reached their survey limit or dropped out of the study and new participants were recruited. Participants were placed in the first panel group (before August 9) and 8 in the second group (after August 8) for up to 10 rounds of survey to reduce the participation burden on individuals. Due to the different implementation of the policy in the 4 countries of the UK, we limit the analysis of this article to participants who reported living in England. • 21 June at the earliest: all legal restrictions on social contacts must be lifted and other sectors of the economy must be reopened. Ministers also hope to be able to decide whether restrictions on marriages can be lifted 1This period is classified as “relaxed restrictions”; However, this period also included a period of different social restrictions for the Christmas holidays. Contact matrices showed overall higher contacts between all age groups during each period compared to lockdown 1, with an increase in clustering around elements of the diagonal matrix indicating higher contact rates between people of the same age (Fig. 6). This led to higher estimates of baseline reproduction number under controlled conditions (Rc).

The periods with the highest CR were between July and August 2020, reflecting an easing of lockdowns and government incentives encouraging the public to dine in restaurants, where contact increased particularly among 18- to 49-year-olds and older adults (>60). When schools reopened in September 2020 after the summer holidays, the number of child-to-child contacts increased 3.17 times (95% CI 3.06 to 3.27) compared to lockdown 1 and 2.12 (95% CI 2.05 to 2.18) assuming equal transmissibility across all age groups or assuming age-related communicability estimates relevant to SARS-CoV-2. Discussion 21: Line 389: Please avoid wording that implies causation: “Although the easing of restrictions led to an increase in contact, this did not necessarily happen immediately. A: The distribution of the number of environment-specific contacts before and after the introduction of each restriction. Figure S1B. Change the contacts for each restriction. 5. Summary: Methods and results: Please provide details on the implementation of the population survey (e.g.

Internet banners and social media ads, email campaigns). We calculated the average number of contacts in different environments: at home, at work and at school (all educational institutions, including daycares, kindergartens, universities and colleges) and “other” (mainly leisure and social contacts, including shopping). The average number of contacts was influenced by some participants who reported a very high number of contacts (often in a work context) compared to the rest of the panel. The distribution of reported contacts is distorted with high variance. The average number of contacts shown here was calculated by censoring the maximum number of contacts recorded to 50 per person per day to reduce the variance, meaning that we counted each person who reported more than 50 contacts as if they had reported 50 contacts to reduce people`s weight, who report a high number of contacts on average. We have found in previous analyses that 50-contact censorship most closely reflects changes in contact versus changes in reproduction number at time t (Rt) over time, as estimated in the Real-time Assessment of Community Transmission (REACT) study, a large home-based screening study conducted in the UK to quantify COVID-19 transmission and infections [20,21]. Our study is a longitudinal experiment on nature. For each participant, we have a pre-implementation observation and a post-constraint observation. Comments shall not exceed 16 days from the date of entry into force of the restriction.

This allows the individuals in our study to have their own control and thus reduces the effect of variations between individuals as well as the effect of longer-term temporal trends. The types of contacts reported were classified as home contact, work contact, school contact and other environments. After the lifting of lockdown 1 from late May to early July 2020, registered contacts remained low until August 2020 (Fig. 1B). Contact patterns recovered much faster after the second lockdown in December 2020, despite ongoing restrictions (in England, there was a system of tiered restrictions that was reinforced after the second lockdown). Reported contacts were very low during the Christmas period, with a slight easing of restrictions during the festive period in some parts of England and stricter restrictions in others. Finally, adult contact rates remained low during the third lockdown, with significant restrictions in place until the end of the study period in March 2021. The pattern of school opening and closing was the main determinant of children`s contacts (Figures 1B and 1C). 7. Summary: Lines 35 to 37: Please clarify whether this applies to adults or children, as contact results for both age groups have been presented above: “This shows a sustained decline in social contacts compared to an average of 11.08 (95% CI 10.54 to 11.57) contacts per participant in total, as measured by the POLYMOD study on social contacts 2005/06. The prime minister said England would start “reclaiming our freedoms” – all legal restrictions on people`s social contacts due to end by June 21. In this study, we observed that registered contacts decreased dramatically from pre-pandemic levels (measured in the POLYMOD study), with changes in reported contacts correlated with government responses during the pandemic.