Immunizations (pediatrics): Clinical sciences

Immunizations promote immunity by activating the adaptive immune system to produce microbe-specific antibodies. These circulating antibodies protect against infection by binding to invading microbes and disabling them.

Based on standardized schedules, routine vaccinations are performed during well-child visits at specific ages. You should keep in mind some special considerations that may arise, such as international travel or an immunocompromised status, that may alter the usual sequence of immunization. Families will often have questions or concerns about vaccines, and you play an important role in providing education about vaccine safety and benefits!

Now, in order to determine which vaccine to give, first you need to assess your patient’s age. At birth, infants should receive their first dose of the hepatitis B vaccine within 24 hours of life, to prevent vertical transmission from mother to baby.

Hepatitis B immunization also protects against acute and chronic hepatitis B infection, which is a known cause of liver disease; hepatocellular carcinoma; and liver failure.

Here’s a clinical pearl! For infants weighing less than 2 kilograms at birth, delay their first dose of the hepatitis B vaccine until 1 month of age, or until discharged from the hospital, as long as the maternal status for hepatitis B surface antigen, or HBsAg for short, is negative.

On the other hand, in cases where the maternal HBsAg status is positive or unknown, administer hepatitis B immune globulin, or HBIG, plus a dose of the hepatitis B vaccine within 12 hours of birth. Remember, though, this dose shouldn’t count as part of their vaccine series. In other words, this patient will receive three additional doses of the hepatitis B vaccine, for a total of four doses!

Next up are vaccines given at 2 months of age. First, all infants should receive their second dose of the Hepatitis B vaccine.

Next, they should receive their first dose of the rotavirus vaccine. This vaccine protects them against the rotavirus infection.

Rotavirus is typically associated with vomiting and diarrhea; but, in severe cases, it might lead to dehydration and require hospitalization.

Next is the first dose of the DTaP vaccine, which protects against three toxin-producing bacteria.

The first one is Corynebacterium diphtheriae, which produces the diphtheria toxin that affects mucous membranes of the throat and nose, and can lead to severe upper airway obstruction and respiratory distress. This condition is also known as diphtheria.

The second is Clostridium tetani, which produces the tetanus toxin that affects neuromuscular transmission and results in painful muscle contractions and spasms.

Finally, there’s Bordetella pertussis, which produces the pertussis toxin that typically results in a specific paroxysmal coughing called whooping cough. In young infants, Bordetella pertussis infection can also cause apnea!

Here’s another clinical pearl! Since babies won’t receive their first dose of the DTaP vaccine until they’re two months old, this leaves them unprotected during the first two months of life. Accordingly, to provide passive immunity during this vulnerable period, administer the DTaP booster, or Tdap, to all your pregnant patients between 27 and 36 weeks of gestation, so antibodies can cross the placenta!

Also give the first dose of the Hib vaccine, which protects against Haemophilus influenzae type B infection,

and the first dose of the pneumococcal conjugate vaccine, which protects against Streptococcus pneumoniae. Both bacteria can cause otitis media, pneumonia, and bacterial meningitis.

Finally, all infants should receive the inactivated poliovirus vaccine that protects against poliovirus infection, which can cause poliomyelitis, paralysis, and even respiratory failure.

Next, at the 4 month visit, infants should receive the second dose of rotavirus, DTaP, Hib, pneumococcal, and poliovirus.

Similarly, at the 6 month visit, they should receive their third dose of HepB, DTaP, pneumococcal, and inactivated poliovirus vaccines.

Keep in mind that some vaccines have different formulations that come with unique dosing schedules. For example, the rotavirus and Hib vaccines have two-dose and three-dose formulations; so, if the infant is receiving the three-dose formulation, at this point, they should receive their third dose!

At this age, infants can also receive their first doses of influenza and COVID-19 vaccines. The influenza vaccine, commonly called the flu shot, protects from influenza, an acute respiratory illness that can cause viral pneumonia and may require hospitalization. When they receive their first influenza vaccine, they should receive a second dose one month later. Subsequently, they can receive the influenza vaccine annually.

On the flip side, the COVID-19 vaccine protects against variants of SARS-CoV-2 virus, which causes an acute respiratory infection that can progress to viral pneumonia and acute respiratory distress syndrome, requiring hospitalization.

The first time a child receives a vaccine against COVID-19, they should receive either a two- or three-dose series. After that, guidelines vary based on age, and include boosters to protect against newer coronavirus strains.