Every vaccination includes a pre-vaccination screening. Its purpose is to find people who need to postpone vaccination or must not be vaccinated. This article follows Parts V and VI of the book Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026).

What to tell the doctor

Be sure to mention:

Current illness, current medicines, chronic diseases.
Birth defects, premature birth.
History of allergies.
Strong reactions after a previous dose: high fever, prolonged crying, rash, widespread swelling at the injection site.

Proof of previous vaccination must come from a vaccination record or card. Without it, the person is considered not immune and is vaccinated according to the schedule. In general, no tests are needed before deciding to vaccinate.

Source: Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part V, section 2.1, p. 190.

Must not be vaccinated (contraindications)

Grade III or higher anaphylaxis after a previous dose of a vaccine with the same components.
History of intussusception: no oral rotavirus vaccine.
Congenital immunodeficiency: no oral polio vaccine (OPV).
Other contraindications according to each manufacturer's instructions.

Source: Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part V, section 2.2.3, p. 191.

Postpone and vaccinate later

Fever of 38°C or higher, or low body temperature of 35.5°C or lower (measured in the armpit): vaccinate when the temperature is stable.
Acute illness or infectious disease: vaccinate after recovery.
Organ failure (respiratory, heart, kidney or liver failure, reduced consciousness…): vaccinate when stable.
Grade II anaphylaxis after a previous dose: refer for screening and vaccination at a hospital.
Reactions that get stronger with each dose of the same vaccine: vaccinate at a hospital.
Infants under 2,000 g: screening and vaccination at a hospital until they reach 2,000 g.
Unstable congenital or chronic disease of the heart, lungs, digestive or urinary tract, blood, or cancer: screening at a hospital, vaccinate when the disease is stable.

Source: Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part V, section 2.2.4, pp. 191–192.

Postponing live vaccines only

Within 3 months after immunoglobulin (except hepatitis B immunoglobulin): postpone live vaccines until 3 months have passed.
Currently taking or recently stopped high-dose systemic corticosteroids (equivalent to prednisone 2 mg/kg/day or more), chemotherapy or radiotherapy: postpone live vaccines until 14 days after treatment ends.
Suspected or confirmed severe congenital immunodeficiency: postpone live vaccines and refer for examination at a hospital.

Source: Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part V, section 2.2.4, pp. 191–192.

Allergy to vaccine components

Egg protein is present in yellow fever, influenza, measles and MMR vaccines, because they are produced in embryonated chicken eggs. People with a history of egg allergy must tell the doctor.
People allergic to gelatin need special caution with gelatin-containing vaccines.
People allergic to neomycin should not receive vaccines containing neomycin.

Source: Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part VI, section 3, p. 202.

Not reasons to postpone

Premature babies: vaccinate according to actual age, with full doses as for full-term babies. Weight only affects the hepatitis B schedule.
Breastfeeding: does not affect vaccination of the mother or the baby. Exceptions: Qdenga is contraindicated during breastfeeding; yellow fever vaccine is only given when really necessary.
Taking antibiotics: no need to postpone, except for oral typhoid vaccine.
People with bleeding disorders: can still be vaccinated, possibly by subcutaneous or intradermal injection instead. Tell the health worker about the risk of bleeding.

Source: Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026), Part VI, sections 6.1–6.3 and 6.5, pp. 204–206.