Impact of the COVID-19 pandemic on gastrointestinal infection trends in England, February-July 2020

Abstract

Objective: To establish the impact of the first 6 months of the COVID-19 outbreak response on gastrointestinal (GI) infection trends in England.

Design: Retrospective ecological study using routinely collected national and regional surveillance data from seven UK Health Security Agency coordinated laboratory, outbreak and syndromic surveillance systems using key dates of UK governmental policy change to assign phases for comparison between 2020 and historic data.

Results: Decreases in GI illness activity were observed across all surveillance indicators as COVID-19 cases began to peak. Compared with the 5-year average (2015-2019), during the first 6 months of the COVID-19 response, there was a 52% decrease in GI outbreaks reported (1544 vs 3208 (95% CI 2938 to 3478)) and a 34% decrease in laboratory confirmed cases (27 859 vs 42 495 (95% CI 40 068 to 44 922)). GI indicators began to rise during the first lockdown and lockdown easing, although all remained substantially lower than historic figures. Reductions in laboratory confirmed cases were observed across all age groups and both sexes, with geographical heterogeneity observed in diagnosis trends. Health seeking behaviour changed substantially, with attendances decreasing prior to lockdown across all indicators.

Conclusions: There has been a marked change in trends of GI infections in the context of the COVID-19 pandemic. The drivers of this change are likely to be multifactorial; while changes in health seeking behaviour, pressure on diagnostic services and surveillance system ascertainment have undoubtably played a role, there has likely been a true decrease in the incidence for some pathogens resulting from the control measures and restrictions implemented. This suggests that if some of these changes in behaviour such as improved hand hygiene were maintained, then we could potentially see sustained reductions in the burden of GI illness.

Keywords: COVID-19; epidemiology; gastrointestinal infections.

Figure 1

Gastrointestinal (GI) outbreaks and GI pathogens* reported to the UK Health Security Agency between week 1 and week 31 2020 and the 5-year weekly average (95% CI), indicating key public health measures introduced during the COVID-19 response. *Organisms: Campylobacter spp, STEC O157, STEC non-O157, Listeria spp, non-typhoidal Salmonella spp, typhoidal Salmonella, Shigella spp, norovirus, Cryptosporidium spp and Giardia sp. SGSS, Second Generation Surveillance System.

Figure 2

Laboratory-confirmed gastrointestinal pathogens reported to the UK Health Security Agency between week 1 and week 31 2020 and the 5-year weekly average (95% CI), by COVID-19 outbreak phase. (A) Norovirus; (B) Cryptosporidium spp; (C) Giardia sp; (D) Shigella spp; (E) STEC; (F) Salmonella spp and (G) Campylobacter spp.

Figure 3

Laboratory-confirmed gastrointestinal pathogen* cases reported to the UK Health Security Agency between week 1 and week 31 2020 and the 5-year weekly average (95% CI), by COVID-19 outbreak phase and age group. (A) <1 year of age, (B) 1–4 years of age, (C) 5–14 years of age, (D) 15–64 years of age, (E) 65–80 years of age and (F) >80 years of age. *Organisms: Campylobacter spp, STEC O157, STEC non-O157, Listeria spp, non-typhoidal Salmonella spp, typhoidal Salmonella, Shigella spp, norovirus, Cryptosporidium spp and Giardia sp.

Figure 4

Laboratory-confirmed gastrointestinal cases* by UK Health Security Agency region and COVID-19 outbreak phase, percentage change compared with the 5-year average for the region. *Organisms: Campylobacter spp, STEC O157, STEC non-O157, Listeria spp, non-typhoidal Salmonella spp, typhoidal Salmonella, Shigella spp, norovirus, Cryptosporidium spp and Giardia spp.

Figure 5

Syndromic indicators for phases 1–7 of the COVID-19 response, 2020 and 2019: (A) daily emergency department attendances for gastroenteritis as a percentage of total attendances and 7-day moving average. (B) Percentage of total contacts for gastroenteritis in general practitioner (GP)-out of hours services with a read code and as a 7-day moving average. (C) Daily incidence rate and 7-day moving average (adjusted for weekends and bank holidays) for gastroenteritis in GP-in hours services. (D) Daily ‘diarrhoea’ and ‘vomiting’ calls as a percentage of total calls and 7-day moving average.

Figure 6

Number of gastrointestinal outbreaks reported to the UK Health Security Agency by outbreak setting between phases 1 and 7 of the COVID-19 response, with the lower bound* of the 5-year average 95% CI indicated by diamonds. *Central estimate and upper band of historic data not shown due to small numbers reported in 2020.