Vaccinations, and the questions people actually have

Most parents with questions about vaccination are not opposed to it — they want the questions answered properly, and appointments rarely have time.

Why the schedule is timed as it is

Not arbitrary.

Vaccines are given at the earliest age at which they produce a reliable immune response and before the age at which the disease poses the greatest risk.

Whooping cough is most dangerous in the youngest infants, which is why the primary course starts at around eight weeks in many countries and why vaccination in pregnancy is offered — maternal antibodies protect the baby in the weeks before their own vaccination takes effect.

Measles vaccination is given after maternal antibodies have waned enough not to interfere with the response, which is why it comes around the first birthday.

Multiple doses are needed because the immune response builds with each, and boosters maintain it.

Common concerns, answered

Too many at once. The immune system responds to enormous numbers of antigens daily from the ordinary environment.

The number of antigens in the entire modern schedule is far lower than in older vaccines because of improved manufacturing.

Studies comparing outcomes in children receiving the full schedule with those receiving fewer or delayed vaccines have not found benefit from delay, and delay leaves the child unprotected for longer.

Autism. The original study proposing a link was retracted, its author was struck off, and subsequent studies involving millions of children across many countries have found no association.

This is one of the most thoroughly investigated questions in modern epidemiology.

Ingredients. Aluminium salts are used as adjuvants in tiny quantities, and infants are exposed to more aluminium from diet.

Thiomersal is no longer used in routine infant vaccines in most countries.

Formaldehyde residues are far below the amounts produced naturally in the body.

Natural infection. It does produce immunity, at the price of the disease itself — measles causes encephalitis and death in a proportion of cases and suppresses immunity to other infections for years afterwards, which is a well-documented phenomenon.

Herd immunity. It protects those who cannot be vaccinated — newborns, the immunosuppressed, those with certain conditions — and it requires high coverage, which is why individual decisions have collective consequences.

What to expect afterwards

Common and short-lived.

Redness, swelling and tenderness at the injection site.

Irritability and being unsettled.

Mild fever, usually within a day or two, though the MMR-type vaccines can produce a delayed reaction around six to ten days later with fever and sometimes a rash, which is expected.

Reduced feeding and extra sleepiness.

Paracetamol may be given for distress; guidance in some countries specifically recommends prophylactic paracetamol with certain meningococcal vaccines because of the fever rate, so it is worth asking.

Cuddling, feeding and distraction help, and there is evidence that breastfeeding during or after the injection reduces pain.

When to seek help after a vaccination

A high fever that does not settle, or fever in a very young baby.

A baby who is unusually floppy, unresponsive or difficult to rouse.

A seizure.

Spreading redness and swelling with heat, which may indicate infection rather than a reaction.

And any signs of a severe allergic reaction, which is very rare, happens within minutes, and is the reason clinics ask you to wait — swelling of the face or throat, difficulty breathing, or collapse, requiring emergency treatment.

When to delay

Fewer situations than people assume.

A minor illness with or without a low fever is not a reason to postpone.

A significant febrile illness generally is, temporarily.

Specific medical conditions, immunosuppression and certain allergies require individual advice, and live vaccines have particular considerations.

Prematurity is not a reason to delay — preterm babies are vaccinated according to their actual age, not corrected age, because they are at higher risk.

Catching up

Always possible.

A missed vaccine does not mean starting again, and catch-up schedules exist for children of any age.

Moving countries, having lost records, or having declined previously are all situations services handle routinely without judgement.

Where to get information

National health services, paediatric societies and the World Health Organization publish accessible material with the reasoning included.

A health visitor, practice nurse or paediatrician will discuss specific concerns, and asking for a longer appointment to do so is entirely reasonable.

Social media is where the misinformation is, and the material designed to alarm is considerably better produced than the material designed to inform, which is worth being conscious of.

General information only, not medical advice. Schedules vary by country — consult your health visitor, practice nurse or a qualified clinician about vaccination for your child.