Vertical transmission of HIV

Export Indicator

Estimated percentage of children newly infected with HIV in the past 12 months due to vertical transmission

What it measures / Ce qui est mesuré / Qué mide / Что он измеряет

When compared with values from previous years, this indicator shows the impact of providing women with antiretroviral medicines and retaining them in care to reduce vertical transmission of HIV.

Rationale / Fondement / Justificación / Обоснование

Efforts have been made to increase access to interventions that can significantly reduce vertical transmission of HIV, including treatment regimens and strengthening counselling on infant feeding. The impact of interventions for preventing vertical transmission in reducing the number of children newly infected with HIV through vertical transmission needs to be assessed.

For a given prevalence of HIV among pregnant women, the number of children living with HIV and the prevalence of HIV among children should decrease as the coverage of interventions for preventing vertical transmission and the use of more effective regimens increase.

Numerator / Numérateur / Numerador / Числитель

Estimated number of children newly infected with HIV in the previous 12 months from vertical transmission

(Although the denominator is limited to births in the past 12 months, the numerator can include children infected by HIV during the breastfeeding period and thus the birth might have occurred more than 12 months earlier. The indicator is thus actually a ratio and not a true percentage.)

Denominator / Dénominateur / Denominador / Знаменатель

Estimated number of births to women living with HIV in the previous 12 months

Calculation / Calcul / Cálculo / Расчет

Numerator/denominator

Method of measurement / Méthode d’évaluation / Método de medición / Метод измерения

Modelled estimates are used for global reporting, using standardized regional and global probabilities of vertical transmission based on global evidence, applied to national population-level estimates of pregnant women living with HIV annually.

The probability of vertical transmission differs depending on the coverage of prevention of vertical transmission and antiretroviral therapy among pregnant and breastfeeding women, and (for women accessing prevention of vertical transmission services) the timing of initiating antiretroviral therapy, the antiretroviral therapy regimen received, and infant feeding practices. The respective transmission probabilities are embedded and applied in the Spectrum model.

Spectrum requires the following national data inputs, for years applicable, for the estimation:

the number of pregnant women living with HIV receiving antiretroviral medicines, by the timing of treatment initiation (before conception, early in the pregnancy or late in the pregnancy);
the proportion of pregnant women retained on antiretroviral medicines at the time of delivery;
the number of women receiving antiretroviral medicines after delivery during breastfeeding (postpartum);
for women living with HIV and receiving antiretroviral medicines, the percentage whose infants have stopped breastfeeding by age of the child in months (0–35 months);
for women living with HIV but not receiving antiretroviral medicines, the percentage whose infants have stopped breastfeeding by age of the child in months (0–35 months);
among breastfeeding women receiving antiretroviral medicines, the percentage who drop out each month.

Spectrum outputs the following epidemic estimates, for all years:

incidence among breastfeeding women;
number of cases of HIV and rate of vertical transmission of HIV, stratified by the period of transmission (pre- or postpartum) and prevention of vertical transmission/antiretroviral therapy/infant feeding status of the mother–infant pair;
number of women living with HIV giving birth, by age group.

Not enough information is available about non-perinatal HIV transmission routes for children to include these cases in Spectrum. These additional modes of transmission are believed to cause only a small fraction of overall cases of HIV among children. The Spectrum output “New HIV infections for children 0–1 years” is not recommended for programmatic use, because some children older than one year will acquire HIV from breastfeeding.

Measurement frequency / Fréquence de mesure / Frecuencia de medición / Частота измерения

Annually

Disaggregation / Ventilation / Desglose / Разбивка данных

None.

Strengths and weaknesses / Forces et faiblesses / Puntos fuertes y débiles / Преимущества и недостатки

Strengths. Over time, this indicator assesses the ability of programmes to prevent vertical transmission. The modelled estimate is preferred because measuring this indicator directly is very difficult. The modelled estimate overcomes multiple challenges to the direct measurement of vertical transmission:

1. Following up mother–child pairs is difficult, especially at the national level, because of the lag in reporting and the multiple health facility sites that mother–child pairs may visit for the wide range of services for preventing vertical transmission and child-care interventions delivered over a timespan.

2. Children (especially those living with HIV) may die before they are tested to determine whether transmission has occurred.

3. A directly measured indicator will not capture women and their children who do not attend programmes, possibly because of high levels of stigma.

4. Most directly measured values will not include women who seroconvert while breastfeeding.

Weaknesses. The Spectrum-estimated indicator is only as good as the assumptions and data used in the model. In countries where caesarean delivery is practised widely, the indicator may overestimate vertical transmission. Across all settings, the estimation assumes that programmatically reported provision of antiretroviral medicines could underestimate vertical transmission in cases of patient non-adherence or non-consumption.

The indicator does not capture any possible efforts to reduce vertical transmission by preventing maternal infections or by reducing the number of unintended pregnancies among women living with HIV.

In countries with available data, high facility attendance and high coverage of routine confirmatory testing, efforts should be made to monitor the impact by directly assessing the percentage of children living with HIV among those born to women living with HIV. All countries should make efforts to monitor the HIV status and survival of children born to women living with HIV, gathered during follow-up health-care visits.

Further information / Informations complémentaires / Información adicional / Дополнительная информация

Consolidated guidelines on person-centred HIV strategic information: strengthening routine data for impact. Geneva: World Health Organization, 2022 (https://www.who.int/publications/i/item/9789240055315)

Related Indicators

BI.4 Final MTCT rate, 2020, WHO Consolidated HIV strategic information guidelines: driving impact through programme monitoring and management (https://www.who.int/publications/i/item/consolidated-hiv-strategic-information-guidelines).

Tags / Etiqettes / Etiquetas / теги

Global AIDS Monitoring