The biology of the virus is the same at every age: same mechanisms, same immune target, same drug families. What changes in a child are the conditions in which that biology unfolds — and the differences are deep enough to justify a medicine of its own.
Five differences that govern everything
| How infection happens | The great majority of children are infected by their mother, during pregnancy, delivery or breastfeeding. Paediatric prevention therefore begins in obstetrics: see mother-to-child transmission. |
|---|---|
| Viral load | During the first year of life it reaches values far higher than in adult primary infection, and falls slowly. An infected infant is in a heavier virological situation from the outset. |
| Reference values | Absolute CD4 counts vary enormously with age in the early years. Under five, clinicians therefore use the CD4 percentage rather than the absolute figure — an adult threshold applied to an infant means nothing. |
| Pharmacology | Absorption, distribution and elimination differ in the neonatal period, then in infancy, then in older children. Doses are calculated by weight or body surface and recalculated as the child grows. |
| Natural history | Untreated, it is bimodal: a minority progress very fast and severely in the first years, the majority far more slowly. That rapid form is what made paediatric HIV so lethal, and it is what early treatment abolishes. |
The sixth difference, and the decisive one
A child does not take their treatment: it is given to them. Adherence therefore depends not on the child but on the structure around them — a parent often ill themselves, a family fractured by the disease, an institution, sometimes a secret. It is the factor behind most treatment failures, and no molecule corrects it.
Diagnosis before 18 months: a classic trap
The usual HIV test looks for antibodies. A newborn carries their mother's, and these persist for up to 18 months. A positive test in an infant proves nothing: it says the mother is seropositive, not the child.
Diagnosis rests on detecting the virus itself — nucleic acid amplification, a PCR. The recommended schedule pairs a test at birth or around four to six weeks with further tests until exposure ends, breastfeeding included. A positive result is confirmed on a second sample, and treatment starts without waiting for that confirmation.
Rolling out molecular tests that can be run at the point of care, returning a result in hours rather than weeks, has been one of the most useful advances of the past decade: it stops children being lost between the sample and the laboratory report.
Treatment today
The present principle admits no exception: every infected child is treated, whatever their age, clinical stage or CD4 count, and as early as possible. Waiting for immune decline, as was done in the 1990s, belongs to history.
- The reference regimen combines three drugs around an integrase inhibitor — dolutegravir — recommended from the first weeks of life and from three kilograms.
- Formulations were long the bottleneck. Paediatric dispersible tablets dosed for small weights, available only recently, finally allow the recommended regimen to reach the youngest children.
- The goal is an undetectable viral load, with the same consequences as in adults: no disease progression, and no sexual transmission in adulthood.
- Monitoring combines viral load, CD4 percentage, growth and development — in a child, a growth curve picking up again is as telling a marker of success as any number.
A counter-intuitive lesson from practice
Some children do very well clinically and immunologically — growth resumed, back at school, CD4 rising — while their viral load remains imperfectly controlled. Clinical experience suggests not stacking up regimen changes in pursuit of undetectability at any cost: a child doing well on a regimen they tolerate is often worth more than a child exhausted by a fifth line.
The gap that remains: children are treated less than adults
This is the global blind spot, and it is widening. About 1.4 million children under fifteen live with HIV. Just over half receive antiretroviral treatment, against close to eight adults in ten. Several hundred thousand children are therefore infected and untreated.
The gap between children and adults has not narrowed: it has widened over the past decade. The causes are known — infant testing not done or not returned, paediatric formulations unavailable or too expensive, mothers lost to follow-up after delivery, and a market too small to interest manufacturers.
Adolescence, the most fragile period
A child infected at birth and well treated now reaches adulthood. That is this medicine's most complete success — and it is also where failures concentrate. Adolescence gathers everything that undermines adherence: growing autonomy, weariness with a treatment taken since always, the weight of a secret, fear of rejection, and the question of a romantic life.
- Disclosure to the child happens gradually, in stages suited to their age, not all at once in adolescence. A school-age child can and should understand why they take a treatment.
- Transition to adult services is a documented breaking point: it is prepared months ahead and is not merely a file transfer.
- Sexual life is prepared for too: undetectable viral load, condoms for other infections, contraception, and information on preventive treatment for a partner.
What this page is based on
It takes up and updates the framework of a university dissertation on the paediatric cohort of the Armand-Trousseau hospital, completed with the current state of international guidance. The original work is presented in Seventy-eight children, 1993-1998.
Where to discuss it
Care for a child living with HIV belongs to a specialist paediatric team, not an isolated consultation. Family associations do what medicine does not: break the isolation, help carry the secret or let go of it. See HIV and AIDS, mother-to-child transmission and what a cohort of 78 children showed.