The arrival of a new baby may be a cue for grandparents and other relatives to review their vaccination records. With respiratory virus season underway and the United States facing its worst measles outbreak in decades, immunized family members can help protect newborns who are too young for many vaccines.

Babies are especially vulnerable during their first weeks because they rely heavily on antibodies passed from their mother and the immunity of people around them. “For that six months, zero to six months, they are really vulnerable and at risk, and we have to protect them,” said Dr. Dhaval Desai, a physician at The Atlanta Internists.

The US Centers for Disease Control and Prevention recommends that anyone around a newborn be current on routine vaccines. Particular attention goes to the seasonal flu vaccine and the tetanus, diphtheria and pertussis vaccine, commonly called Tdap.

Grandparents may not receive the same vaccination reminders that mothers hear during pregnancy and a baby’s first year. “This is a great time to make sure all vaccines are up to date,” said Dr. Lori Solomon, associate professor and chair of family and community medicine at New York Medical College.

Dr. Michael Warren, chief medical and health officer at the maternal and infant health nonprofit March of Dimes, said vaccines can keep grandparents healthy while helping protect babies whose immune systems are still developing. He advised grandparents to consult a healthcare professional and become current on vaccines before the baby arrives.

The Tdap vaccine protects against tetanus, diphtheria and pertussis, or whooping cough. For babies and young children, pertussis can cause violent coughing, breathing difficulties, pneumonia, convulsions, permanent brain damage or death.

“Pertussis is whooping cough,” Desai said. “It is a debilitating cough disease. We see babies stop breathing. It is a very frightening thing. Most recover from it, but it is something we want to prevent. So Tdap would be one of my non-negotiables for a new grandparent.”

Seasonal flu activity remains low nationally but is rising in many parts of the country, with activity higher than usual for this point in the season. Influenza can quickly cause serious complications in babies and toddlers, including pneumonia, extreme dehydration, brain inflammation or death.

Everyone age 6 months and older is generally urged to receive an annual flu shot. Dr. Ari Brown, a Texas pediatrician, said vaccine protection lasts about six months in older adults, so September or early October is recommended for coverage during the typical winter flu season.

RSV is another respiratory virus that can cause severe illness in babies because thick mucus can obstruct their small airways. Solomon said people at age 50 with certain conditions, including asthma, heart disease and insulin dependent diabetes, should discuss the RSV vaccine with their doctor, while healthy adults receive it at age 75 or older.

Covid-19 vaccination continues to be associated with a lower hospitalization risk, including for older adults and infants who face increased danger from severe disease. Dr. Celine Gounder, an infectious disease specialist at NYU Langone Health, said a seasonal shot “protects you and lowers the chance” of bringing the virus home.

“The scariest thing a parent can get is a positive Covid test in a baby because you can’t do anything except supportive care,” Desai said. Infants are not old enough for treatments such as the prescription medication Paxlovid.

More than 4,500 confirmed measles cases have been reported nationwide to the CDC. An ongoing Pennsylvania outbreak has become the country’s largest and deadliest in more than 30 years, and infants are among those who died this year.

Two doses of the measles, mumps and rubella vaccine provide about 97% protection against measles. “If you’re unsure about your measles immunity, there’s no harm in getting another shot of MMR,” Gounder said.

The CDC considers people born before 1957 immune because most contracted measles during childhood, Gounder said. Those born in 1957 or later without a record of a dose should receive at least one dose.

Measles can spread through airborne viral particles that remain infectious for as long as two hours after an infected person leaves an area. Infants and young children face a greater risk of severe disease and complications.

Vaccination should ideally be completed before visiting a newborn at home or in the hospital. Solomon recommended vaccination at least 30 days before the due date, while Desai said four to six weeks before birth provides enough time for most vaccines to begin producing antibodies.

Most vaccines can be given on the same day in different arms, although some people may need multiple doses. Gounder said that if the live injected MMR and varicella vaccines are not administered on the same day, they must be given at least 28 days apart.

Vaccines are not the only safeguard. Gounder advised grandparents to stay away when ill, wash their hands before holding the baby and avoid kissing the baby’s face, especially during respiratory virus season.

Desai offered grandparents a memorable alternative: “Kiss the toes, not the nose.” He also encouraged them to follow adult vaccination guidelines appropriate for their age to protect their health and remain available for their grandchild.