Booster vaccination: important questions and answers

A booster vaccination is an extra dose of a vaccine. If possible it should be administered before the protection provided by initial immunisation diminishes. Its purpose is to maintain or restore, and prolong, the protection provided by the vaccine. Other vaccinations besides the one for COVID-19 also lose their effect over time and should be renewed. For example, the FOPH recommends getting regular boosters for the vaccination against diphtheria and tetanus (lockjaw).

Initial immunisation involves one or more vaccinations that result in the establishment of immune protection against a specific pathogen and its consequences. It triggers an immune response that confers both rapid protection and an immune memory. The immune protection achieved can last for a varying length of time depending on the vaccine and the pathogen. It can be maintained or increased and extended again with a booster vaccination.

A booster is a renewed vaccination against a pathogen. It is administered months after initial immunisation to refresh the immune protection. The booster vaccination reactivates the immune memory created by initial immunisation, and this quickly restores and prolongs immune protection. Some vaccinations work a whole life long, while others have to be refreshed. A booster vaccination differs from initial immunisation in that it leads to sufficient immune protection again within a short period of time with the administration of a (possibly smaller) single dose of vaccine.

The Federal Vaccination Commission (EKIF) and the Federal Office of Public Health (FOPH) recommend that anyone aged 12 or over receive a booster vaccination with an mRNA vaccine if complete initial immunisation was 4 months or more ago.

The booster vaccination reminds the immune system of the pathogen. The protection the vaccine provides against severe cases is increased and extended again. It’s important to realise that with the current virus variants, the vaccination hardly protects at all and only briefly against infection and mild illness. You can get COVID-19 despite having had the vaccination.

The COVID-19 vaccines authorised in Switzerland were developed to work against the original virus (including the Alpha variant). With the current variants, the vaccination hardly protects at all and only briefly against infection and mild illness.

The mRNA vaccines provide good protection against severe COVD-19 disease requiring hospitalisation. But the protection provided by initial immunisation declines rapidly for all the current variants. With the booster you can increase your protection again. The risk of a severe case of COVID-19 requiring hospitalisation can be substantially reduced. A booster is therefore recommended from four months after complete initial immunisation.

Some vaccine manufacturers are working on modified vaccines against new variants. However, it is still unclear whether, when and how they will be used in Switzerland in the future.

Basically it does not matter which of the two available mRNA vaccines is used. Exceptions:

• People aged from 18 to 29 should preferably receive the Pfizer/BioNTech vaccine for their booster.
• The recommendation is for the Pfizer/BioNTech vaccine to be favoured for vaccinating those aged from 12 to 17.

If the same vaccine is not available, however, the other mRNA vaccine can also be used.

People who have been vaccinated with the Janssen viral vector vaccine are recommended to have their booster with an mRNA vaccine (Pfizer/BioNTech or Moderna), provided this is possible from a medical point of view.

People aged 18 to 29 are recommended to favour a booster vaccination with the Pfizer/BioNTech vaccine. The recommendation is for the Pfizer/BioNTech vaccine to be favoured for vaccinating those aged from 12 to 17.

This is because in very rare cases, inflammation of the heart muscle or the pericardium has been observed in the 14 days after the vaccination. Most of these cases were mild and could be treated effectively. Among people under age 30 such inflammations were observed more frequently after vaccination with the Moderna vaccine. The recommendation that the Pfizer/BioNTech vaccine should be favoured for people under 30 may help reduce this very small risk even further.

However, the following applies to both mRNA vaccines: the benefits of COVID-19 vaccination also outweigh the potential risks for people under 30. People under 30 can also receive the Moderna vaccine if the Pfizer/BioNTech vaccine is not available at the vaccination centre. Inflammation of the heart muscle or pericardium occurs much more frequently after infection with the coronavirus than after vaccination.

The booster vaccination is also recommended for pregnant women from the second trimester and for women who are breastfeeding.

A confirmed coronavirus infection and one dose of an mRNA vaccine at an interval of at least 4 weeks (regardless of the sequence) results in complete initial immunisation. In this case, a second vaccination corresponds to a booster for people who have recovered if it is administered from 4 months after full initial immunisation.

We recommend a booster even if you have had a coronavirus infection since initial immunisation. According to new findings, an infection does not provide sufficient protection from a severe case of the disease. You can be vaccinated from four weeks after the infection (taking account of the minimum interval of four months following the last COVID-19 vaccination).

You can be vaccinated from four weeks after the infection (taking account of the minimum interval of four months following the last COVID-19 vaccination).

The same side effects can occur after the booster as after the vaccination(s) for initial immunisation. In most cases they are mild and last only a short time. These are normal signs that the body is building the desired protection against the coronavirus.

Cases of nettle rash have been reported after a booster vaccination, and a possible link is currently being investigated.

An additional booster is currently recommended for anyone aged 80 and over. We also recommend an additional booster vaccination for people with a severely weakened immune system due to illness or medication; in this case, consult your doctor.
An additional booster can be given from four months after the last vaccination. It increases the protection against another severe case of COVID-19, at least for a certain period of time.

Have been infected with the coronavirus since your last vaccination? Since this infection does not significantly increase your protection against severe disease, we recommend an additional booster. You can be vaccinated from four weeks after the infection (taking account of the minimum interval of four months following the last COVID-19 vaccination).

No, you should not wait. This is because it is not yet clear when adapted vaccines will be available in Switzerland or how they will be used. A booster with the current mRNA vaccines greatly enhances the protection against severe forms of the disease caused by Omicron.

The vaccination is recommended for anyone aged 16 years and older from 4 months after complete initial immunisation.

You are less well protected after one dose of the viral vector vaccine than after initial immunisation with an mRNA vaccine. For better protection, we recommend that between 28 days to 4 months after vaccination with the viral vector vaccine, you supplement the initial immunisation with a dose of an mRNA vaccine from Moderna or Pfizer/BioNTech.

To renew and extend the protection provided by the vaccine, we recommend a booster for anyone aged 18 years and older after initial immunisation with the viral vector vaccine. The booster increases and extends protection against falling severely ill with coronavirus.

We recommend a booster vaccination preferably with an mRNA vaccine (Pfizer/BioNTech or Moderna) from 4 months after full vaccination (initial immunisation), provided this is possible from a medical point of view.

Are you unable to be vaccinated with an mRNA vaccine for medical reasons? Or do you not want to be vaccinated with an mRNA vaccine? Then we recommend you have a booster with the Janssen viral vector vaccine from 2 months after initial immunisation.