Research and analysis

Acute hepatitis B: national enhanced surveillance report January to March 2021

Updated 24 January 2024

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) being 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 (see Acute hepatitis B: guide to national enhanced surveillance).

Following the reporting of clusters of acute hepatitis B in 2016, an HPZone context ‘Acute hepatitis B’ was added for monitoring of acute cases.

Methods

Acute hepatitis B cases recorded in two different ways and entered on HPZone between January and March 2021 were extracted. HPZone Context ‘Acute Hepatitis B’ data includes personally identifiable information, which therefore allows for the rapid identification of cases and the requesting of samples directly from laboratories for avidity and molecular characterisation at 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 the 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 March 2021, 59 cases of acute hepatitis B were reported onto the HPZone Dashboard across England (confirmed, probable and possible).

Overall, the cases entered on HPZone have been declining since 2011: from 513 in that year to 199 in 2020. Monthly cases since 2010 in England are shown in figure 1. In 2015 there was a slight increase in cases likely caused by the 2015 outbreak of acute hepatitis B in men who have sex with men who identify as heterosexual (1).

Figure 1. Cumulative cases of acute hepatitis B in England entered on HPZone Dashboard: 2010 to March 2021. (Note: 2021 data is provisional)

Figure 2 shows the number of cases reported with personal identifiable information through HPZone Context by month. The 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 March 2021 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 March 2021 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 March 2021, in both the HPZone Context data set and the HPZone Dashboard data set, age and sex was well reported (>98.3%). Where sex was known (58 out of 59) males accounted for 67.2% of cases (39 out of 58). The median age of those with acute HBV was 43 years (IQR: 30 to 56): 44 (IQR: 35 to 58) for males and 41 (IQR: 26 to 54) for females.

The age distribution by sex is presented in table 1. The highest proportion of cases were in those between 35 and 44 years of age. The highest proportion in males was in the 35 to 44 year group; in females it was among those between 25 and 34.

Table 1. Number and proportion of acute HBV cases from HPZone Dashboard by sex and age group during January to March 2021

Age group	Female	Male	Unknown	Total
Under 15	0 (–)	0 (–)	0 (–)	0 (–)
15 to 24	4 (21%)	4 (10%)	0 (–)	8 (14%)
25 to 34	5 (26%)	6 (16%)	0 (–)	11 (19%)
35 to 44	2 (11%)	11 (30%)	1 (100%)	14 (25%)
45 to 54	3 (16%)	6 (16%)	0 (–)	9 (16%)
55 to 64	4 (21%)	8 (22%)	0 (–)	12 (21%)
65 and over	1 (5%)	4 (10%)	0 (–)	5 (9%)
Total:	19	39	1	59

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 21 samples submitted to the VRD as part of the enhanced surveillance programme, 5 (24%) samples were confirmed to be from individuals with chronic hepatitis B and 8 (38%) were confirmed to be from individuals with acute hepatitis B infection. The avidity testing in 2 samples was classified as undetermined where it was not possible to confidently assign an HBV infection status and 6 samples were not tested.

Not all cases with samples forwarded to the VRD could be matched to cases in HPZone Context; this could either be due to a case not being entered on HPZone or it could be due to the case being entered in a previous quarter.

A total of 8 confirmed acute cases could be genotyped during the January to March 2021 quarter; the distribution of genotypes is shown in table 2. Consistent with trends seen in 2019 and 2020, genotype A was the most commonly reported genotype with 78.6% of cases (2). Additional sub genotype analysis of the A viruses indicated 3 to be A1 and 8 to be A2. The distribution of genotypes seen in UKHSA regions is shown in figure 4.

Table 2. Genotype distribution and proportions of acute hepatitis B cases tested at VRD in January to March 2021

Acute genotype	Number of cases	Proportion of cases
A*	11	69%
B	0	–
C	0	–
D*	4	25%
E*	1	6%
F	0	–
Total*	16	–

*Two undetermined (E=1 and D=1) and 6 not tested (A=5 and D=1).

Figure 4. Genotypes of acute samples sent to VRD by UKHSA region*

*Excludes 3 where region was unknown (genotypes A2=2 and D5=1).

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 in January to March 2021 remained low and consistent with annual trends for the same timeframe. 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 MSM 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. Shankar AG, Mandal S, Ijaz S (2016). ‘An outbreak of hepatitis B in men who have sex with men but identify as heterosexual’. BMJ Sexually Transmitted Infections, volume 92 issue 3: page 227.

2. Public Health England (2019). ‘Acute Hepatitis B (England): annual report for 2018’.