COVID-19 vaccine surveillance

Pooled data from Scotland, England, and Wales was used to investigate the possible association of cerebral venous sinus thrombosis (CVST) following dose 1 of a COVID-19 vaccine.

In this study, a small, elevated risk of CVST events following vaccination with ChAdOx1 nCoV-19 (AZD1222; (Oxford–AstraZeneca, Vaxzevria)) was observed, but not BNT162b2 (Pfizer–BioNTech, Comirnaty).

More information, including a plain English summary, is available on the EAVE II webpage for first dose ChAdOx1 and BNT162b2 COVID-19 vaccinations and cerebral venous sinus thrombosis.

Learn more about this article and project on the University of Edinburgh's website.

A study was conducted to investigate hospital admissions from neurological complications in the 28 days after a first dose of COVID-19 vaccine, and after a SARS-CoV-2-positive test.

Although there was an increased risk of neurological complications in those who received COVID-19 vaccines, the risk of these complications was greater following a positive SARS-CoV-2 test.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for neurological complications after a first dose of COVID-19 vaccination and after a SARS-CoV-2-positive test.

The study found that the first dose of BNT162b2 (Pfizer–BioNTech, Comirnaty) vaccine has no link with increased risk of any of the adverse events included in the analysis.

The first dose of the ChAdOx1 nCoV-19 (AZD1222; (Oxford–AstraZeneca, Vaxzevria)) vaccine was associated with a small increased risk of Idiopathic thrombocytopenic purpura (ITP)(low platelet count).

No increased risk was found for venous thromboembolic events after having the ChAdOx1 nCoV-19 (AZD1222; (Oxford–AstraZeneca, Vaxzevria)).

More information, including a plain English summary and infographic, is available on the EAVE II webpage for first-dose COVID-19 vaccines and thrombocytopenic, thromboembolic and hemorrhagic events in Scotland.

General population

A small number of COVID-19 deaths are still expected in vaccinated people, especially in vulnerable individuals where the vaccine or the immune response may not have been effective.

Evidence has shown that COVID-19 vaccination is highly effective in protecting against COVID-19 related death in adults and children.

At-risk population

Older people, those with multiple chronic conditions, and those with specific underlying health conditions are at increased risk of COVID-19 associated hospitalisation and death after the initial vaccine booster and should therefore be prioritised for additional boosters, and COVID-19 therapeutics.

Older age groups

In the over 60s and people living in long-term care facilities, a second COVID-19 vaccine booster dose, which includes the most recent Bivalent COVID-19 mRNA vaccine, improved protection against death, compared to a single COVID-19 vaccine booster.

At-risk conditions

The immunocompromised population have a higher risk of COVID-19 death and vaccine effectiveness can be lower than the general population. However, immunocompromised individuals that have received first booster vaccinations are at reduced risk of COVID-19 death compared with those who had only completed their primary vaccination schedule.

General population

In adults, several studies estimating vaccine effectiveness against COVID-19 associated hospitalisation have shown high levels of protection against the Alpha, Delta, and Omicron variants. Protection against COVID-19 associated hospitalisation peaks in the early weeks or months after receipt of a COVID-19 vaccination but can reduce or wane over time since vaccination.

Waning protection is greater among older adults and among adults with at-risk conditions. However, a booster dose of vaccine offers increased protection against COVID-19 associated hospitalisation.

In children and young people, vaccine effectiveness against COVID-19 associated hospitalisation is estimated to be higher for two doses compared with one dose. Although waning has been observed, protection against severe COVID-19 outcomes remained high following the second dose.

A limitation of some hospitalisation studies is that they often cannot determine whether someone is in hospital with or because of COVID-19.

If people test COVID-19 positive on admission to hospital, it may not be the primary reason for admission, and instead an incidental finding.

This causes a problem when trying to calculate vaccine effectiveness estimates against COVID-19 associated hospitalisation. Inclusion of incidental cases may result in lower estimates of effectiveness against hospitalisation than reality.

At-risk population

Older age groups

In the over 60s and people living in long-term care facilities, a second COVID-19 vaccine booster dose offered improved protection against hospitalisation for COVID-19, compared to a single COVID-19 vaccine booster. Protection peaks a few weeks after vaccination before waning. The Bivalent mRNA vaccine booster has been shown to lower COVID-19 associated hospitalisation and mortality rates.

At-risk conditions

The immunocompromised population have been reported to be at higher risk of hospitalisation due to COVID-19 than the general population. However, for immunocompromised people, a first booster vaccination and a subsequent Bivalent mRNA vaccine booster is thought to provide greater protection against COVID-19 associated hospitalisation compared with those who had only completed their primary vaccination schedule.

General population

Evidence suggests that you may test positive and have symptomatic COVID-19, even if you are vaccinated. In adults there is increased protection following vaccination but this protection wanes over time

Similarly in children and young people there was increased protection following vaccination which waned over time

A limitation of studies is that they often cannot determine the severity of symptoms. For example, one person may only have mild COVID-19 symptoms such as a runny nose for one day. Another person may have severe symptoms such as long-term fatigue and breathing issues.

These people would have different outcomes of infection, but they would both be recorded as having symptoms.

This could result in an under or overestimate of vaccine effectiveness.

At-risk population

Older age groups

In the over 60s and people living in long-term care facilities, studies suggest a second booster dose provides greater protection against symptomatic COVID-19 infection than those who have one booster dose but protection wanes over time

At-risk conditions

For immunocompromised people, a first booster vaccine is thought to provide greater protection against severe COVID-19 infection compared with those who only complete their primary vaccination schedule but protection wanes over time.

Studies looking at long COVID-19 have shown a decrease in incidence after a first dose of vaccine, with further reductions after a second dose.

Vaccine effectiveness against mortality

General population

1. BNT162b2 Vaccine Booster and Mortality Due to Covid-19
2. UKHSA COVID-19 vaccine surveillance report
3. Vaccine effectiveness of two-dose BNT162b2 against symptomatic and severe COVID-19 among adolescents in Brazil and Scotland over time: a test-negative case-control study
4. Effects of Vaccination and Previous Infection on Omicron Infections in Children

At-risk population

1. Severe COVID-19 outcomes after full vaccination of primary schedule and initial boosters: pooled analysis of national prospective cohort studies of 30 million individuals in England, Northern Ireland, Scotland, and Wales
2. Fourth dose of BNT162b2 mRNA COVID-19 vaccine in a nationwide setting
3. Effectiveness of a second BNT162b2 booster vaccine against hospitalization and death from COVID-19 in adults aged over 60 years
4. Short term, relative effectiveness of four doses versus three doses of BNT162b2 vaccine in people aged 60 years and older in Israel: retrospective, test negative, case-control study
5. Hospitalized patients with severe coronavirus disease 2019 during the omicron wave in Israel: benefits of a fourth vaccine dose
6. Association of Receipt of the Fourth BNT162b2 Dose with Omicron Infection and COVID-19 Hospitalizations Among Residents of Long-term Care Facilities
7. Effectiveness of a Second COVID-19 Vaccine Booster Dose Against Infection, Hospitalization, or Death Among Nursing Home Residents — 19 States, March 29–July 25, 2022
8. Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study
9. Effectiveness of Second mRNA COVID-19 Booster Vaccine in Immunocompromised Persons and Long-Term Care Facility Residents
10. Effectiveness of Second mRNA COVID-19 Booster Vaccine in Immunocompromised Persons and Long-Term Care Facility Residents
11. The effect of immunosuppressants on the prognosis of SARS-CoV-2 infection
12. In-hospital mortality among immunosuppressed patients with COVID-19: Analysis from a national cohort in Spain
13. Clinical characteristics and outcomes of immunosuppressed patients hospitalized with COVID-19: experience from London
14. COVID-19: Third dose booster vaccine effectiveness against breakthrough coronavirus infection, hospitalisations and death in patients with cancer: A population-based study
15. Effectiveness of the Bivalent mRNA Vaccine in Preventing Severe COVID-19 Outcomes: An Observational Cohort Study (Preprint)

Vaccine effectiveness against hospitalisation

General population

1. UKHSA COVID-19 vaccine surveillance report
2. Clinical characteristics and outcomes of immunosuppressed patients hospitalized with COVID-19: experience from London
3. COVID-19: Third dose booster vaccine effectiveness against breakthrough coronavirus infection, hospitalisations and death in patients with cancer: A population-based study
4. Duration of protection against mild and severe disease by covid-19 vaccines
5. Effectiveness of the Pfizer-BioNTech and Oxford-AstraZeneca vaccines on covid-19 related symptoms, hospital admissions, and mortality in older adults in England: test negative case-control study
6. Interim findings from first-dose mass COVID-19 vaccination roll-out and COVID-19 hospital admissions in Scotland: a national prospective cohort study
7. Effectiveness of BNT162b2 and ChAdOx1 nCoV-19 COVID-19 vaccination at preventing hospitalisations in people aged at least 80 years: a test-negative, case-control study
8. Two-dose ChAdOx1 nCoV-19 vaccine protection against COVID-19 hospital admissions and deaths over time: a retrospective, population-based cohort study in Scotland and Brazil
9. Effectiveness of the COVID-19 vaccines against hospitalisation with Omicron sub-lineages BA.4 and BA.5 in England
10. Effectiveness of mRNA-1273 against infection and COVID-19 hospitalization with SARS-CoV-2 Omicron subvariants: BA.1, BA.2, BA.2.12.1, BA.4, and BA.5 (Pre-print)
11. Vaccine effectiveness of two-dose BNT162b2 against symptomatic and severe COVID-19 among adolescents in Brazil and Scotland over time: a test-negative case-control study
12. Effectiveness of BNT162b2 Vaccine against Omicron in Children 5 to 11 Years of Age
13. UKHSA COVID-19 vaccine surveillance report
14. High vaccine effectiveness against severe Covid-19 in the elderly in Finland before and after the emergence of Omicron

At-risk population

1. Fourth dose of BNT162b2 mRNA COVID-19 vaccine in a nationwide setting
2. Effectiveness of a second BNT162b2 booster vaccine against hospitalization and death from COVID-19 in adults aged over 60 years
3. Short term, relative effectiveness of four doses versus three doses of BNT162b2 vaccine in people aged 60 years and older in Israel: retrospective, test negative, case-control study
4. Hospitalized patients with severe coronavirus disease 2019 during the omicron wave in Israel: benefits of a fourth vaccine dose
5. Association of Receipt of the Fourth BNT162b2 Dose with Omicron Infection and COVID-19 Hospitalizations Among Residents of Long-term Care Facilities
6. Effectiveness of a Second COVID-19 Vaccine Booster Dose Against Infection, Hospitalization, or Death Among Nursing Home Residents — 19 States, March 29–July 25, 2022
7. Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study
8. Effectiveness of Second mRNA COVID-19 Booster Vaccine in Immunocompromised Persons and Long-Term Care Facility Residents
9. High vaccine effectiveness against severe Covid-19 in the elderly in Finland before and after the emergence of Omicron
10. Protection by a fourth dose of BNT162b2 against omicron in Israel
11. Effectiveness of a Fourth Dose of COVID-19 mRNA Vaccine Against Omicron Variant Among Elderly People in Singapore
12. Effectiveness of Second mRNA COVID-19 Booster Vaccine in Immunocompromised Persons and Long-Term Care Facility Residents
13. The effect of immunosuppressants on the prognosis of SARS-CoV-2 infection
14. In-hospital mortality among immunosuppressed patients with COVID-19: Analysis from a national cohort in Spain
15. COVID-19 vaccine effectiveness against omicron (B.1.1.529) variant infection and hospitalisation in patients taking immunosuppressive medications: a retrospective cohort study
16. Efficacy of covid-19 vaccines in immunocompromised patients: systematic review and meta-analysis
17. COVID-19: Third dose booster vaccine effectiveness against breakthrough coronavirus infection, hospitalisations and death in patients with cancer: A population-based study
18. Risk of COVID-19 breakthrough infection and hospitalization in individuals with comorbidities
19. Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19–Associated Hospitalization Among Immunocompetent Adults Aged ≥65 Years
20. Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19–Associated Emergency Department or Urgent Care Encounters and Hospitalizations Among Immunocompetent Adults
21. Effectiveness of the Bivalent mRNA Vaccine in Preventing Severe COVID-19 Outcomes: An Observational Cohort Study (Preprint)

Vaccine effectiveness against symptomatic disease

General population

1. UKHSA COVID-19 vaccine surveillance report
2. Interim findings from first-dose mass COVID-19 vaccination roll-out and COVID-19 hospital admissions in Scotland: a national prospective cohort study
3. Effectiveness of BNT162b2 and ChAdOx1 nCoV-19 COVID-19 vaccination at preventing hospitalisations in people aged at least 80 years: a test-negative, case-control study
4. Two-dose ChAdOx1 nCoV-19 vaccine protection against COVID-19 hospital admissions and deaths over time: a retrospective, population-based cohort study in Scotland and Brazil
5. Covid-19 Vaccine Effectiveness against the Omicron (B.1.1.529) Variant
6. Severity of omicron variant of concern and effectiveness of vaccine boosters against symptomatic disease in Scotland (EAVE II): a national cohort study with nested test-negative design
7. Vaccine effectiveness of two-dose BNT162b2 against symptomatic and severe COVID-19 among adolescents in Brazil and Scotland over time: a test-negative case-control study
8. Effects of Vaccination and Previous Infection on Omicron Infections in Children
9. Effectiveness of BNT162b2 Vaccine against Omicron in Children 5 to 11 Years of Age
10. Effectiveness of Bivalent mRNA Vaccines in Preventing Symptomatic SARS-CoV-2 Infection, September–November 2022

At-risk population

1. Fourth dose of BNT162b2 mRNA COVID-19 vaccine in a nationwide setting
2. Association of Receipt of the Fourth BNT162b2 Dose with Omicron Infection and COVID-19 Hospitalizations Among Residents of Long-term Care Facilities
3. Effectiveness of a Second COVID-19 Vaccine Booster Dose Against Infection, Hospitalization, or Death Among Nursing Home Residents — 19 States, March 29–July 25, 2022
4. Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study
5. Effectiveness of Second mRNA COVID-19 Booster Vaccine in Immunocompromised Persons and Long-Term Care Facility Residents
6. High vaccine effectiveness against severe Covid-19 in the elderly in Finland before and after the emergence of Omicron
7. Protection by a fourth dose of BNT162b2 against omicron in Israel
8. Effectiveness of a Fourth Dose of COVID-19 mRNA Vaccine Against Omicron Variant Among Elderly People in Singapore
9. COVID-19: Third dose booster vaccine effectiveness against breakthrough coronavirus infection, hospitalisations and death in patients with cancer: A population-based study
10. COVID-19 vaccine effectiveness against omicron (B.1.1.529) variant infection and hospitalisation in patients taking immunosuppressive medications: a retrospective cohort study
11. Efficacy of covid-19 vaccines in immunocompromised patients: systematic review and meta-analysis
12. Risk of COVID-19 breakthrough infection and hospitalization in individuals with comorbidities

Other vaccine studies

1. The effectiveness of vaccination against long COVID. A rapid evidence briefing
2. Trajectory of long covid symptoms after covid-19 vaccination: community based cohort study

An analysis of severity of Omicron variant BA.2 infection compared to Omicron variant BA.1 and SARS-CoV-2 B.1.617.2 (Delta). Results show individuals with BA.2 are at similar risk for COVID-19 than if infected with the original variant. Three doses of COVID-19 vaccine provide reasonable protection against both symptomatic infection and death.

Read the severity of BA.2 variant and vaccine effectiveness against symptomatic disease in Scotland article.

Study examining neonates in Scotland with SARS-CoV-2 infection; the risk of infection by maternal and infant characteristics; and hospital admissions associated with confirmed neonatal infections. Confirmed neonatal SARS-CoV-2 infection was uncommon over the first 23 months of the pandemic in Scotland. Two-thirds of neonates with confirmed infection had an associated hospital admission. There were no neonatal deaths among babies with confirmed infection.

More information, including a plain English summary, is available on the EAVE II webpage for confirmed SARS-CoV-2 infection in Scottish new-borns 2020–2022.

This paper looked at who is at higher risk of serious illness from an Omicron infection after receiving a third or booster dose of COVID-19 vaccine. Results showed that risk of COVID-19 hospital admission or death reduced for people who had a booster vaccine.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for severe COVID-19 post vaccination primary booster.

A national, population-based, matched cohort study assessing associations between COVID-19 vaccination and miscarriage prior to 20 weeks gestation and, separately, ectopic pregnancy. Study showed that having a COVID-19 vaccine does not put women at higher risk of either miscarriage or ectopic pregnancy. The same is true of SARS-CoV-2 infection, but estimates were less precise.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for early pregnancy outcomes following COVID-19 vaccination and SARS-COV-2 Infection in pregnant women.

This study assessed and compared short-term pregnancy outcomes after SARS-CoV-2 Delta and Omicron variant infection in pregnancy. Results indicated that pregnant women infected with SARS-CoV-2 were substantially less likely to have a preterm birth or maternal critical care admission during the Omicron-dominant period than during the Delta-dominant period.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for pregnancy outcomes following Delta and Omicron SARS-CoV-2 infection in Scotland.

Research on the uptake, safety, and effectiveness Pfizer-BioNTech COVID-19 vaccine over time for people aged 12-17 in Scotland. It showed that having two doses of Pfizer-BioNTech vaccine gives people aged 12-17 good protection against symptomatic infection in the SARS-CoV-2 Delta and Omicron variant periods. There was no link between vaccination and any of the potential health outcomes studied. However, vaccine protection against symptomatic infection was short-lived.

More information, including a plain English summary, is available on the EAVE II webpage for children and young people vaccine uptake, safety, and effectiveness.

A research letter which looked at people who had not received a COVID-19 vaccine.  Results found a similar number of unvaccinated men and women, average age was 42.4 years, most unvaccinated people lived in urban areas, the largest proportion lived in the most deprived areas, and most unvaccinated people had no underlying health conditions recorded. However, a significant number had three or more underlying conditions recorded.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for unvaccinated adults in Scotland.

Collaborative study on COVID-19 vaccine effectiveness against symptomatic infection and severe outcomes in Brazilian and Scottish adolescents who received two-doses of the Pfizer-BioNTech vaccine. Results showed that during the Omicron variant period, protection given by the Pfizer- BioNTech vaccine against severe COVID-19 remained strong 98 days after the second dose.

However, vaccine protection against symptomatic infection began to wane 27-days post-second dose.  More information, including a plain English summary and infographic, is available on the EAVE II webpage for vaccine effectiveness in adolescents in Brazil and Scotland.

Journal article on COVID-19 hospital admissions, and the effectiveness of vaccine boosters, in people infected by the Omicron variant in Scotland. Results indicated that people were three times less likely to be admitted to hospital with the Omicron variant than with Delta.  Although offering the greatest protection against Delta, the booster dose of vaccination offered substantial additional protection against the risk of symptomatic COVID-19 for Omicron compared with 25 weeks or more after the second vaccine dose.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for Omicron booster effectiveness against symptomatic disease.

Research that looked at patterns of COVID-19 disease and hospital admissions in Scotland when the Delta variant was most common. Data showed that the number of SARS-CoV-2 infections and COVID-19 hospitalisations were consistently higher in people who were unvaccinated than those who were vaccinated, during the Delta era.

More information, including a plain English summary, is available on the EAVE II webpage for infections and COVID-19 Hospitalisations in Scotland in the Delta era.

Study investigating the association between time since two doses of ChAdOx1 nCoV-19 (AZD1222; (Oxford–AstraZeneca, Vaxzevria)) vaccine and risk of severe COVID-19 outcomes in Scotland (where the Delta variant was dominant), with comparative analyses in Brazil (where the Delta variant was uncommon). Study found waning vaccine protection against COVID-19 hospital admissions and deaths in both Scotland and Brazil within three months of the second vaccine dose.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for vaccine protection against COVID-19 severe outcomes over time in Scotland and Brazil.

Research found that COVID-19 deaths were extremely uncommon in people who tested positive 14 days or more after their second dose of the Pfizer-BioNTech or Oxford-AstraZeneca vaccine. The risk profiles also suggest that older adults, and particularly men, with multiple long term health conditions should continue to be cautious.

More information, including a plain English summary, is available on the EAVE II webpage for characteristics and risk of COVID-19-related death after two vaccine doses in Scotland.

Study estimating the level of protection that vaccines give against COVID-19 deaths from infection with the Delta variant. Both the ChAdOx1 nCoV-19 (AZD1222; (Oxford–AstraZeneca, Vaxzevria)) and BNT162b2 (Pfizer–BioNTech, Comirnaty) vaccines provided strong protection, which varies slightly by age group.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for vaccine efficacy against the Delta Variant in Scotland.

Investigation on the number of people in Scotland who died from or admitted to hospital with COVID-19 after at least one vaccine dose. Results showed COVID-19 associated hospitalisations and deaths were uncommon 14 days or more after the first vaccine dose. Sociodemographic and clinical features known to increase the risk of severe disease in unvaccinated populations were also associated with severe outcomes in people receiving their first dose of vaccine.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for COVID-19 hospital admissions and deaths post vaccination.

Research presented in this article suggested the Delta variant was associated with approximately double the risk of hospitalisation compared with the Alpha variant, with risk of admission particularly increased in those with five or more relevant comorbidities. Both the Oxford–AstraZeneca and Pfizer–BioNTech COVID-19 vaccines were effective in reducing the risk of SARS-CoV-2 infection and COVID-19 hospitalisation in people with Delta, but these effects on infection appeared to be diminished when compared to those with the Alpha.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for impact of the Delta variant in Scotland.

Journal article looking at the risk of hospital admission for COVID-19 after one dose of COVID-19 vaccine found substantial reductions in the risk of hospital admission due to COVID-19 in Scotland.

More information, including a plain English summary and infographic, is available on the EAVE II webpage for first-dose mass COVID-19 vaccination roll-out in Scotland.