(Last update 21 January 2022)

This page presents the current knowledge on COVID-19 vaccines, available evidence and epidemiological context as of 21 January 2022. Due to the rapidly changing epidemiological situation in the EU/EEA, we recommend regularly checking ECDC’s homepage for any new information on variants of concern and COVID-19 vaccines.

Availability of COVID-19 vaccines in the EU/EEA

As of January 2022, five COVID-19 vaccines have received conditional marketing authorisation in the EU/EEA, following evaluation by the European Medicines Agency (EMA), and are part of the EU Coronavirus Vaccines Strategy Portfolio: Comirnaty (BNT162b2) by BioNTech and Pfizer, Spikevax (mRNA-1273) by Moderna, Vaxzevria (AZD1222) by AstraZeneca, COVID-19 Vaccine Janssen (Ad26.COV 2.5), and Nuvaxovid (NVX-CoV2373) by Novavax. COVID-19 vaccine product-specific information can be found on EMA’s webpage COVID-19 Vaccines.

EMA has initiated rolling reviews for the following COVID‑19 vaccines: Sputnik V (Gam-COVID-Vac) by Gamaleya, COVID-19 Vaccine (Vero Cell) Inactivated by Sinovac Life Sciences, Vidprevtyn by Sanofi Pasteur, and VLA2001 by Valneva [1]. Information on the vaccine roll-out, including information on the number of vaccine doses distributed to countries by the manufacturers and the number of doses administered to individuals by age group/other priority groups is displayed by the COVID-19 vaccine tracker on ECDC’s website.

Efficacy, effectiveness and duration of immunity - EU/EEA authorised COVID-19 vaccines

COVID-19 vaccine efficacy

COVID-19 vaccines licensed for use in the EU/EEA have been shown during clinical trials to be highly effective in providing protection against symptomatic SARS-CoV-2 infection and severe COVID-19. Table 1 shows the overall vaccine efficacy of the licensed vaccines after completed vaccination.

Table 1. Overall efficacy of COVID-19 vaccines authorised for use in the EU

Vaccine name

Overall % vaccine efficacy

Date of study launch and data cut-off for primary analysis of efficacy


95.0% (95% CI 90.3, 97.6) (≥16 years) (against COVID-19) [2]

27 July 2020–9 October 2020


94.1% (95% CI 89.3,96.8) (≥18 years) (against COVID-19 illness regardless of severity)[3]

27 July 2020–21 November 2020


61.2% (95% CI 41.0,75.7) (≥18 years) (against COVID-19 with two standard doses)


90.0% (95% CI 67.4-97.0) (against COVID-19 with a low dose followed by a standard dose)


70.4% (95.8% 54.8-80.6) (overall vaccine efficacy against COVID-19 across both dosing groups)


23 April 2020–4 November 2020

COVID-19 Vaccine Janssen*

66.9% (95% CI 59.03, 73.40) (≥18 years) (against COVID-19 of any severity)


76.7% (95% CI 54.6 to 89.1) (against severe-critical COVID-19) [5]

21 September 2020–22 January 2021


90.4% (95% CI 82.9-94.6) (≥18 years) (against COVID-19 of any severity) [6]


89.7% (95% CI 80.2-94.6) (≥18 years) (against COVID-19 of any severity) [7]

27 December 2020 – 19 April 2021 (US and Mexico)


28 September 2020 – ongoing (UK)

#two-dose schedule

*one-dose schedule

Note: trial end points, study populations and follow-ups differed between the trials. Also, differing incidence of SARS-CoV-2 infection in the population and the prevalence of SARS-CoV-2 variants of concern circulating at the time of the trials may have an effect on efficacy results.

COVID-19 vaccine effectiveness

Since the approval of the first COVID-19 vaccine in the EU/EEA in December 2020, the body of evidence regarding vaccine effectiveness and population impact has grown.

Based on the currently available evidence, vaccine effectiveness of EU-authorised vaccines continues to show strong protection against severe disease, hospitalisation and death following completion of the primary series of vaccination (one dose for COVID-19 Vaccine Janssen or two doses for the other authorised vaccines) in the general population, in residents of long-term care facilities (LTCFs) and in older adults.

For the Delta variant of concern (VOC), vaccine effectiveness against infections and transmission is seemingly reduced compared to the Alpha variant and the wild type (WT) SARS-CoV-2 but continues to be maintained at a high level against severe outcomes [8].

The Omicron VOC is increasing in prevalence in the EU/EEA and is rapidly becoming the dominant variant. The presence of multiple mutations in the spike protein of the Omicron VOC indicates a high likelihood of the reduction of neutralising activity by antibodies induced by infection or vaccination. There are also emerging vaccine effectiveness data for Omicron VOC, with early data suggesting that the studied vaccines do not perform as well against outcomes from Omicron compared to the Delta VOC. Preliminary data show significantly reduced vaccine effectiveness against infection and symptomatic disease from Omicron VOC compared to Delta VOC and this also declines rapidly a few months after a second dose, as well as 10 weeks after a booster dose. Vaccine effectiveness against severe outcomes seems to remain high after a second dose, albeit reduced compared to Delta. Further data are needed to estimate the duration of the protection of COVID-19 vaccines against severe disease from the Omicron VOC [9-13]. According to the evidence currently available, for severe outcomes caused by the Delta variant and the Omicron variant, booster doses will increase protection [14].

Due to the rapidly changing epidemiological situation in the EU/EEA, we recommend regularly checking ECDC’s homepage for any new information relating to variants of concern and COVID-19 vaccines. An update of the evidence of vaccine effectiveness against SARS-CoV-2 infection by severity (mild/moderate disease, severe disease, hospitalisation, death) and duration of immunity can be found in ECDC’s Rapid Risk Assessments, Assessment of the current SARS-CoV-2 epidemiological situation in the EU/EEA, projections for the end-of-year festive season and strategies for response, 17th update, published on 24 November 2021 and also Assessment of the further emergence and potential impact of the SARS-CoV-2 Omicron variant of concern in the context of ongoing transmission of the Delta variant of concern in the EU/EEA, 18th update, published on 15 December 2021.

COVID-19 vaccine duration of immunity, booster doses, and variants

Despite increasing vaccine coverage in the EU/EEA, waning immunity and the circulation of variants with increased transmissibility and decreased vaccine effectiveness need to be considered.

Studies assessing vaccine effectiveness against infection, hospitalisation and death show that there is a decline in vaccine effectiveness against infection, symptomatic infection and onward transmission for EU-authorised COVID-19 vaccines that correlate with time since completion of primary vaccination, which is similar to what was shown in earlier studies analysed in ECDC’s technical report Interim public health considerations for the provision of additional COVID-19 vaccine doses. For Delta VOC, vaccine effectiveness against hospitalisations and deaths continues to remain stable in the majority of studies up to nine months after completion of the primary series, with modest declines observed in older individuals and those with comorbidities [8]. Emerging clinical trial data on the efficacy of booster doses of Comirnaty and observational studies on the effectiveness of booster doses against infection and severe disease show a significant increase in protection against infection and severe disease following a booster dose of Comirnaty in all age groups in the short term (the longest follow-up time in the included studies is approximately 70 days) [14]. However, while vaccines continue to elicit high level of protection against severe COVID-19, substantially lower COVID-19 vaccine effectiveness has been estimated against Omicron infection and symptomatic disease after primary vaccination compared to the Delta variant. Emerging evidence also indicates that vaccine effectiveness against infection (and onward transmission) by the Omicron variant is rapidly decreasing with time after both primary series and after a booster dose [15]. These estimates should be considered as preliminary evidence. For the latest evidence, please monitor ECDC’s website and upcoming risk assessments.

Duration of immunity is a complex issue and, to date, the correlation between measured immunity (e.g. levels of antibodies) and clinical protection from SARS-CoV-2 infection still needs to be established. The presence of memory T-cells could prevent severe disease in infected individuals for a long period of time, although the durability of these cells and role in protecting from infection (and onward transmission) remains unclear.

Recommendations on an additional dose as an extension of the primary vaccination series

In September 2021, ECDC recommended that the option of administering an additional vaccine dose to subjects who may experience a limited response to the primary series of COVID-19 vaccination, such as some categories of immunocompromised individuals (e.g. solid organ transplant recipients) should already be considered. The agency also recommended giving consideration to providing an additional dose to older frail individuals as a precaution, in particular to those living in closed settings (e.g. residents of long-term care facilities) [8]. Following an analysis of studies that showed that an additional dose of Comirnaty and Spikevax increased the ability to produce antibodies against the virus that caused COVID-19 in organ transplant patients with weakened immune systems, on 4 October 2021 EMA’s Committee for Medicinal Products for Human Use (CHMP) recommended that an additional dose of Comirnaty and Spikevax may be given to people with severely weakened immune systems at least 28 days after their second dose [16]. On 26 October 2021, the WHO Strategic Advisory Group of Experts (SAGE) published their ‘Interim guidance recommendations for an extended primary series with an additional vaccination in immunocompromised persons’, in which they recommended that the primary vaccine series in moderately to severely immunocompromised people (such as people with active cancer, transplant recipients, immunodeficiency, HIV, and immunosuppressives) should be extended to include an additional dose for all COVID-19 vaccines that have received WHO Emergency Use Listing. The additional dose in an extended primary series is recommended to be given at least one month and within three months after the primary series in order to increase protection for immunocompromised people [17]. All 30 EU/EEA countries are currently recommending an additional dose as an extension of the primary series to those with weakened immune systems [18].

Recommendations on booster dose

After evaluating data on Comirnaty that showed a rise in antibody levels when a booster dose is given approximately six months after the second dose, EMA’s CHMP concluded that booster doses of Comirnaty may be considered at least six months after the second dose for people aged 18 years and older [16]. Following this recommendation, the CHMP evaluated data on Spikevax that showed that a third dose of Spikevax given six to eight months after the second dose led to a rise in antibody levels in adults whose antibody levels were waning, and on 25 October 2021 concluded that a booster dose of the Spikevax may be considered in people aged 18 years and above at least six months after the second dose [19]. On 15 December 2021, EMA concluded that a booster dose of COVID-19 Vaccine Janssen to be considered at least two months after the first dose to people aged 18 years and older [20]. On 7 December 2021 ECDC and EMA jointly published recommendations and advice on heterologous primary and booster COVID-19 vaccination [21]. Based on the conclusions of mathematical modelling done by ECDC in December 2021, in addition to the potential reduction of vaccine effectiveness against the Omicron VOC, particularly in non-boosted individuals, waning immunity requires a speed up in the deployment of booster doses to reduce an avoidable burden in early 2022. The population impact is expected to be higher if a booster dose is administered to most of the adult population and if this booster dose is given as early as possible, although not before three months after completion of the primary series vaccination course [22]. All 30 EU/EEA countries are recommending booster doses for waning immunity to different population groups [18].

Risk factors for breakthrough infections leading to severe disease after vaccination

Unvaccinated individuals are at a much greater risk of being hospitalised or dying from COVID-19 compared to vaccinated individuals [23]. There is evidence that those who have completed the primary series of vaccination and have breakthrough infections face a significantly lower risk of developing severe disease or requiring hospitalisation in comparison to those who are unvaccinated [24]. Individuals with underlying conditions and weakened immune systems are at an increased risk for breakthrough infections leading to severe disease. There is also some evidence from Israel of an increased risk of breakthrough infections in individuals with a longer time since vaccination (waning of vaccine effectiveness) across all age groups [25]. Such waning appears to be more pronounced in the elderly, as shown by several studies in which they have been shown to develop reduced and less durable immune responses to vaccines than younger people [25-27]. It is therefore important to closely monitor increased incidence of breakthrough infections across age groups and to take into account that EU/EEA countries have prioritised vaccines to older age groups, so they will be among the first to experience waning immunity with time after vaccination. This might also affect the increased incidence of severe breakthrough infections in older age groups, and a similar effect might also be seen in younger age groups with an increased time since vaccination.

COVID-19 vaccine safety

The five EU/EEA authorised COVID-19 vaccines all showed a very good safety profile in clinical trials before receiving recommendations of approval from EMA. Since licensing, EMA, other regulatory agencies and other international bodies have been continuously monitoring the post-authorisation safety of COVID-19 vaccines.

The Pharmacovigilance Risk Assessment Committee (PRAC) of EMA have reviewed several safety events and adapted product information accordingly. Despite the occurrence of rare adverse events, the overall benefits of authorised COVID-19 vaccines in preventing COVID-19 outweigh the risks of side effects [1].


Page last updated 21 Jan 2022