Table 2

Data sources for national surveillance data

Variables (as displayed in text/figures)Source
Conceptions per 100 women in England and WalesOffice of National Statistics (ONS). Conceptions in England and Wales, 2019. Release date: 5 August 2021 (
Abortions per 100 women in England and WalesDepartment of Health and Social Care (DHSC). Abortion statistics, England and Wales: 2020. Updated 4 January (
Chlamydia testing, HIV testing, and sexual health clinical STI-related attendance rates per 100 people in EnglandData from UK Health Security Agency (UKHSA, formerly Public Health England (PHE))
Cervical cancer screening (estimated uptake among women in the same age groups in a comparable sample)Cervical Screening Programme, England 2018-19 (National Statistics). NHS Digital. (accessed 17 March 2022).
Calculation of expected number of women attending screening:
% of all women invited in a single year (all women divided by intervals in between screening)
Women aged 25–49, screened every 3.5 years: 28.6%
Women aged 50–59, screened every 5.5 years: 18.2%
Average coverage 70%
Weighted number of women in each age group in analysis:
Women aged 25–49: 1992
Women aged 50–59: 818
Estimated number of Natsal-COVID-2 women invited to screen in 1 year (# x % invited):
Women aged 25–49 (1992×0.286): 569.712
Women aged 50–59 (818×0.182): 148.876
Total (569.712+148.876) = 718.588
% in Natsal-COVID-2 sample expected to be invited in 1 year (total invited/all aged 25–59):
718.588/2810 = 25.57% invited
% expected uptake (% invited x 0.7)
25.57% x 0.7=17.9% expected uptake
  • Notes. 1. We used data sources from England or England and Wales as a reasonable proxy for Britain (86.7% of participants in Natsal-COVID-2 survey resided in England). 2. Pregnancy and abortion rates were recalculated from published rates to include only women aged 18 or over. Chlamydia testing, HIV testing and clinic attendance included women and men aged 18–44.

  • STI, sexually transmitted infection.