Acute hepatitis B: national enhanced surveillance report January to December 2020
Updated 24 January 2024
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Background
The quarterly reporting of enhanced molecular surveillance of acute hepatitis B is based on clinical reports of acute cases to UK Health Security Agency (UKHSA) entered on HPZone and corresponding samples being submitted to the UKHSA Blood Borne Virus Unit (BBVU) in the Virus Reference Department (VRD) at Colindale.
In 2016, VRD reintroduced anti-hepatitis B core avidity testing alongside genotyping of samples from patients diagnosed with acute hepatitis B – a service which is offered free of charge.
Hospital microbiology and virology departments are requested to send samples to Colindale for confirmation, avidity testing and genotyping as part of the national enhanced surveillance of acute hepatitis B (1).
Following the reporting of clusters of acute hepatitis B in 2016, an HPZone Context ‘Acute hepatitis B’ was added for monitoring of acute cases.
Impact of SARS-CoV-2 (COVID-19)
Following the first cases of SARS-CoV-2 detected in England at the end of January 2020, social and physical distancing measures were introduced in March, requiring people to stay at home, closing businesses and venues. Declines in testing and diagnoses during this period were observed. Reasons for these declines are multifactorial, including, but not restricted to: deployment of staff; disruption to and/or reconfiguration of health services reducing access to testing; disruption to laboratory consumables due to increased demand during the pandemic; and the impact of social and physical distancing measures resulting in fewer opportunities for onward transmission.
Methods
Acute hepatitis B cases – recorded in 2 different ways and entered on HPZone between January 2020 and December 2020 – were extracted.
HPZone Context ‘Acute Hepatitis B’ data includes personally identifiable information, which therefore allows for the rapid identification of cases and request of samples directly from laboratories for avidity and molecular characterisation at VRD, Colindale.
HPZone data without personally identifiable information (HPZone Dashboard) on acute cases was matched to HPZone Context data using a unique identifier. The ‘Acute Hepatitis B’ Context data was matched to laboratory testing data from VRD using Microsoft Access algorithms comparing combinations of the following variables: Surname, First name, Date of birth, Sex and NHS number.
Results
Between January and December 2020, 199 cases of acute hepatitis B were reported onto HPZone Dashboard across England (confirmed, probable and possible). The number of reported cases is lower than observed in previous years, likely to be associated with the impact of the COVID-19 pandemic.
Overall, the cases entered on HPZone Dashboard have been declining since 2011, when 513 cases were recorded, to 287 recorded in 2019. Monthly cases since 2010 in England are shown in Figure 1. In 2015 there was a slight increase in cases likely caused by the outbreak of acute hepatitis B in men who have sex with men who identify as heterosexual (2).
Figure 1. Cumulative cases of acute hepatitis B in England entered on HPZone Dashboard 2010 to December 2020
Note: 2020 data is provisional.
Figure 2 shows the number of cases reported with personal identifiable information through HPZone Context by month. This additional information allows for a letter to be sent to request residual samples directly from laboratories for avidity and molecular characterisation. The line represents the proportion of samples received from laboratories. Figure 3 shows this distribution by region.
Figure 2. January to December 2020 cases entered onto HPZone Dashboard
The line graph (right axis) shows the proportion of HPZone Context cases that had a sample forwarded to VRD.
Figure 3. January to December 2020 cases entered onto HPZone Context and/or entered onto HPZone Dashboard by UKHSA regions
The line graph (right axis) shows the proportion of HPZone Context cases that had a sample forwarded to VRD.
For cases reported between January and December 2020, in both the HPZone Context dataset and the HPZone Dashboard dataset, age and sex was well reported (99%). Where sex was known (197 of 199), males accounted for 66% of cases (130 out of 197). The median age of acute HBV cases was 40 years (IQR: 28 to 52): 43 years (IQR: 29 to 56) for males and 34 years (IQR: 26 to 47) for females. The age distribution by sex is presented in Table 1; the highest proportion of cases was in the 25 to 34 and the 35 to 44 year age groups. The highest proportion in males was 35 to 44 year-olds, while in females the highest proportion was among 15 to 24 year-olds.
Table 1. Number and proportion of acute HBV cases from HPZone Dashboard by sex and age group during January to December 2020
| Age group | Female | Male | Unknown | Total |
|---|---|---|---|---|
| Under 15 | 1 (1.5) | 4 (3.1) | 0 (0.0) | 5 (2.5) |
| 15 to 24 | 14 (20.9) | 18 (13.8) | 0 (0.0) | 32 (16.1) |
| 25 to 34 | 19 (28.4) | 22 (16.9) | 1 (100) | 42 (21.1) |
| 35 to 44 | 13 (19.4) | 26 (20.0) | 0 (0.0) | 39 (19.6) |
| 45 to 54 | 14 (20.9) | 23 (17.7) | 1 (100) | 38 (19.1) |
| 55 to 64 | 2 (3.0) | 21 (16.2) | 0 (0.0) | 23 (11.6) |
| 65 and over | 4 (6.0) | 16 (12.3) | 0 (0.0) | 20 (10.1) |
| Total | 67 | 130 | 2 | 199 |
Avidity testing and molecular characterisation investigations were undertaken on samples linked to cases to confirm the acute hepatitis B diagnosis with additional genotyping and phylogenetic analysis to inform on the diversity of the circulating viruses.
Of the 62 samples submitted to VRD as part of the enhanced surveillance programme, 11 (17.7%) samples were confirmed to be from individuals with chronic hepatitis B and 31 (50%) were confirmed to be from individuals with acute hepatitis B infection. The avidity testing in the remaining 19 samples was classified as undetermined where it was not possible to confidently assign an HBV infection status and one sample was not tested.
A total of 23 confirmed acute cases could be genotyped between January and December 2020. The distribution of genotypes is shown in Table 2. Consistent with trends seen in 2018 and 2019, genotype A was the most commonly reported genotype with 33% of cases (3). Additional sub genotype analysis of the A viruses indicated 3 to be A1 and 7 to be A2. The distribution of genotypes seen in the then Public Health England (PHE) regions is shown in Figure 4.
Table 2. Genotype distribution and proportions of acute hepatitis B cases tested at VRD between January and December 2020
| Acute genotype | Number of cases | Proportion of cases |
|---|---|---|
| A | 11 | 47.8 |
| B | 0 | 0.0 |
| C | 4 | 17.4 |
| D | 5 | 21.7 |
| E | 2 | 8.7 |
| F | 1 | 4.3 |
| Total | 23 | – |
Figure 4. Genotypes of acute samples sent to VRD by then-PHE region
Discussion
Quarterly publication of enhanced molecular surveillance using matched HPZone and reference laboratory confirmatory and typing data with a regional breakdown allows real-time monitoring of acute hepatitis B transmission. The number of acute hepatitis B cases between January and December 2020 remained low and consistent with annual trends for the same timeframe. The impact of the COVID-19 pandemic may have also contributed to low numbers.
Molecular analysis provides insight into the current hepatitis B genotypes circulating in England, although interpretation is limited by the small proportion of samples submitted to VRD. The A2 ‘prisoner variant’ is one of the most common strains and is known to be well-established in the UK gay, bisexual and other men who have sex with men (GBMSM) population.
Other genotypes can indicate a geographical origin which can help provide an understanding of sources of infection and transmission routes. For example, genotype D is associated with South Asia. Timely assignment of cases to the HPZone context and improved submission of samples for molecular characterisation will allow for more comprehensive monitoring of acute hepatitis B infection in England.
References
1. PHE (2016). ‘Acute hepatitis B: guide to national enhanced surveillance’
2. Shankar AG, Mandal S, Ijaz S (2016). ‘An outbreak of acute hepatitis B in men who have sex with men but identify as heterosexual’. BMJ Sexually Transmitted Infections: volume 92, issue 3, page 227
3. PHE (2019). ‘Acute hepatitis B (England): annual report for 2018’