On the day of taking a new dose of the covid-19 vaccine, going to the health center may be accompanied by the question: can I update the vaccine card? Is it wrong to take a dose of the immunizer against covid and a dose against influenza together?
The short answer is: yes, any healthy adult can get more than one vaccine on the same day — preferably in different arms. The longer answer is that it depends on a few factors.
As every rule has its exceptions, there are a few cases in which the application of more than one vaccine followed by another is not recommended.
“In general, most vaccines can be administered on the same day, except when one interferes with the effectiveness of the other, such as yellow fever and MMR in children under 2 years of age, for example”, explains Ronney Mendes, a physician working in São Luís ( MA) and member of the immunization department at Asbai (Brazilian Association of Allergy and Immunopathology).
The age issue is one of the main ones when it comes to vaccines. Although newborns take several bites in a row, experts recommend attention with the combination of vaccines for yellow fever, MMR — which protects against rubella, mumps and measles — and BCG (against tuberculosis).
These three vaccines are called attenuated, meaning they are made with live attenuated (weakened) viruses. In children under 2 years of age, it is best to avoid combining more than one vaccine with attenuated virus, as the effectiveness of immunization is reduced.
“It’s not because of side effects, but because the immune response is lower,” says Viviane de Macedo, an infectious disease specialist at the Santa Casa Hospital in Curitiba (PR) and a professor at the Positivo University.
In very young children, the recommendation is to wait 30 days between the application of each vaccine with attenuated virus. “When I apply an attenuated vaccine, viral replication starts after the fifth day and forms antibodies between 10 and 15 days. If I apply another vaccine, for example, after three days, the immune system diverts its response to fight the new antigen “, explains Lorena de Castro Diniz, coordinator of the Scientific Department of Immunization at Asbai.
The same process can happen in the elderly who need to take more than one vaccine with attenuated virus, such as yellow fever and shingles, for example, and in immunosuppressed adults (such as people with HIV or undergoing chemotherapy). “These are particularities”, says Macedo. Therefore, in these cases, it is better to wait 30 days to take different vaccines.
Now, if the vaccines are inactivated (without the weakened virus), they can be applied on the same day to anyone – including the same limb, as long as there is 2.5 cm of distance between the bites.
Arm pain, headache and fever are some of the symptoms that can appear after the application of some vaccines, but the more vaccines, the more side effects? “Adverse effects are not magnified with more than one vaccine”, says Viviane de Macedo.
According to experts, the side effects of vaccines happen because the immune system has been highly activated and, therefore, the person feels sick — but that does not mean that he is developing the disease from the vaccine.
“It could be that the person already had the infection incubated and happened to take the vaccine, there are several reports of this”, says de Macedo.
Going to the post to get the vaccine against covid-19 is what has most driven the population to update the vaccination card. “The most important thing is this opportunity for vaccination”, says Diniz, from Asbai. Among adults and adolescents, it is safe to take the covid vaccine with other doses against other diseases.
For now, it is not recommended that children be vaccinated on the same day against covid and other diseases. “This restriction is still maintained to facilitate pharmacovigilance data”, explains Mendes. “We already have a lot of safety data on covid vaccination in children, but we are still collecting data on the signs of the disease and the adverse effects of the vaccine”, he adds.
Still, it’s important to keep your little ones vaccines up to date. “Eradicated diseases, such as measles, are returning and this is due to the lack of vaccination”, warns Macedo. “If you are going to take any vaccine, update the card”, he advises.