Insight
Since the first COVID-19 vaccine was authorized for use in the UK in December 2020, the focus of the COVID-19 vaccination program has been and continues to be the reduction of serious illness (hospitalization and mortality) in the population, while protecting the NHS.
As the transition continues from pandemic emergency response to pandemic recovery, the Joint Committee on Vaccination and Immunization (JCVI) has begun considering the COVID-19 vaccination program for 2023. The current era of Omicron is characterized by:
- high levels of population immunity acquired through vaccination and/or natural infection
- lower disease severity compared to infection from previous SARS-CoV-2 variants
Meanwhile, the risk of severe COVID-19 continues to be disproportionately higher among people in older age groups, residents of care homes for the elderly, and people with certain underlying health conditions. . Compared to the initial phases of the pandemic, much more is now known about SARS-CoV2 infection. However, there remains lingering uncertainty regarding the evolution of the virus, the durability and extent of immunity, and the epidemiology of infection. These uncertainties limit the immediate development of a routine vaccination program against COVID-19.
Advice
JCVIThe tentative guidance for planning purposes prior to 2023 is as follows:
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in fall 2023, people at high risk of severe COVID-19 may be offered a booster dose of vaccine in preparation for winter 2023 to 2024
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additionally, for a smaller group of people (such as older people and those who are immunocompromised), an additional booster dose may be offered in spring 2023
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emergency vaccine responses may be required if a new variant of concern emerges with clinically significant biological differences from the Omicron variant
JCVI also advises that:
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the 2021 booster offer (third dose) for people aged 16 to 49 who are not part of a clinical risk group should end in line with the end of the fall 2022 vaccination campaign[footnote 1]
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otherwise healthy people aged 5 to 49 who develop a new health problem in 2023 placing them in a clinical risk group would be offered a primary and/or booster vaccination during the next seasonal vaccination campaign, depending on the case. Vaccination outside of these campaign periods would be subject to individual clinical judgment
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Primary COVID-19 vaccination should evolve, during 2023, towards a more targeted offer during vaccination campaigns to protect those most at risk of severe COVID-19. This would include:
- residents of an aged care home and staff working in aged care homes
- frontline health and social service workers
- all adults aged 50 and over
- people between the ages of 5 and 49 belonging to a clinical risk group, as defined in the Green Paper
- people aged 12 to 49 who are household contacts of immunosuppressed people
- people aged 16 to 49 who are carers, as set out in the Green Paper
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research should be considered to inform the optimal timing of booster vaccinations to protect against severe COVID-19 (hospitalizations and deaths) for groups that have different levels of clinical risk
Considerations
It is estimated that over 97% of adults in England had antibodies to SARS-CoV-2, either through infection or vaccination, by the end of August 2022 (Reference 1). In Britain, an estimated 93-99% of children aged 12-15, and 74-98% of children aged 8-11, had antibodies against SARS-CoV-2 at the end of August 2022 ( references 1 and 2). Natural immunity alone provides good levels of protection against severe COVID-19, while the combination of natural and vaccine-induced immunity (hybrid immunity) is associated with even higher levels of protection (references 3, 4 and 5). This high level of strong population immunity developed over the past 2½ years is regularly monitored by the UK Health Security Agency (UKHSA) public health surveillance programs.
Not all hospitalizations and deaths attributed to SARS-CoV-2 infection are vaccine preventable events. Due to the high transmissibility of the Omicron variant, as well as infection which may be asymptomatic or only mildly symptomatic, individuals requiring hospital care for reasons other than COVID-19 may coincidentally become infected with SARS- CoV-2. Such hospitalizations cannot be prevented by vaccination against COVID-19. On the other hand, some very vulnerable people can develop a severe form of COVID-19 despite their vaccination; these people often have underlying health conditions that also confer a high susceptibility to serious illness from other infections. In the UK, during the Omicron era (until week 43, 2022), the highest hospitalization rates were consistently seen among people aged 75 and over, while infection rates (non-severe disease) were elevated at all ages and especially in younger people (References 6 and 7).
Revised estimates of the number needed to vaccinate (NNV) to avoid hospitalization during the Omicron era indicate that 800 people aged 70 and over should receive a booster in the fall of 2022 (a fourth dose) to avoid hospitalization due to COVID-19. The correspondent NNV for people aged 50-59 is 8,000 and for people aged 40-49 who are not in a clinical risk group, it is 92,500 (Appendix 1).
In November 2021, JCVI boosters advised for healthy adults 40-49 years of age due to epidemiology at the time. With the emergence of the Omicron variant at the end of November 2021, the offer was extended to healthy individuals aged 16 to 39 as part of an emergency response (see JCVI update on advice for COVID-19 vaccination of children and young people and the UK vaccine response to the Omicron variant: JCVI advice). Since April 2022, uptake of the initial booster dose of the COVID-19 vaccine has been less than 0.1% per week among all eligible people under the age of 50 (Figure 62c in reference 8). Based on current data, maintaining the booster (third dose) offer to these groups is considered to be of limited continued value and the overall impact on immunization coverage is negligible.
Primary vaccination offers have been widely available since 2021. Uptake of these vaccine offers has plateaued in recent months across all age groups (Figure 62a in Ref 8). Since the start of 2022, less than 0.01% of eligible people per week over the age of 12 have received a first dose of the COVID-19 vaccine. A more targeted offer of primary vaccination during campaign periods will allow these efforts to be better targeted and NHS resources to be used more effectively.
Although the COVID-19 vaccination program has been very effective overall, there are certain socio-economic and ethnic groups where vaccination coverage remains lower (Reference 6). Tackling health inequities is a long-term effort that cuts across all UK immunization programs. Building trust, and more specifically trust in vaccines, requires consistent and determined investments of time, resources and people. Appropriate and adequate communication should be provided prior to changes to the primary vaccination offer to optimize uptake among those who are eligible but have not yet accepted the vaccination offer.
Future variants and their impact on epidemiology
As the virulence of any new emerging variant cannot be reliably predicted, rapid response measures may be required in the event of substantial changes in population immunity against the circulating dominant variant, including any new variant of concern.
JCVI keep the epidemiology of COVID-19 under review and provide guidance for a rapid response, as needed.
References
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Latest coronavirus (COVID-19) information from the Office for National Statistics (ONS): Antibodies.
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Unpublished data from the UK Health Security Agency.
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Protective efficacy of prior SARS-CoV-2 infection and hybrid immunity against Omicron infection and severe disease: a systematic review and meta-regression.
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Risk of SARS-CoV-2 reinfection and COVID-19 hospitalization in people with natural and hybrid immunity: a retrospective cohort study in the total population in Sweden.
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Protection against Omicron (B.1.1.529) BA.2 reinfection conferred by primary Omicron BA.1 or pre-Omicron infection with SARS-CoV-2 in healthcare workers with and without mRNA vaccination: a test-negative case-control study.
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National influenza and COVID-19 surveillance reports: 2022 to 2023 season.
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Coronavirus (COVID-19) in the UK Dashboard.
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National flu and COVID-19 surveillance report: October 27, 2022 (week 43).