Version July 2025
INTRODUCTION —
Promptly establishing the diagnosis of human immunodeficiency virus (HIV) infection in infants and young children is important because infants who are infected with HIV have a high morbidity and mortality if treatment with antiretroviral therapy (ART) is delayed [1]. Natural history studies early in the epidemic showed that the mortality rate for perinatally infected children who did not receive ART was approximately 50 percent by two years of age [2].
This topic reviews the strategy for diagnosing HIV infection in infants and young children of mothers with known HIV infection or of uncertain HIV serostatus.
We recognize that not all pregnant, postpartum, and lactating individuals identify as women or mothers. The topics discussed here are based on risks driven by pregnancy and transmission of infection to infants and apply regardless of the pregnant person's gender identity. Therefore, throughout this topic, we use the term "woman" to signify a person of the female sex (regardless of gender identity) and the term "mother" to signify the birthing parent of a child (regardless of gender identity or parental rights). For additional information on inclusive language in pregnancy and the postpartum period, please see the recently updated NIAID HIV Language Guide.
The diagnosis of HIV infection in children ≥18 months who were never breastfed is similar to adults and is discussed separately. (See "Screening and diagnostic testing for HIV infection in adults" and "Acute and early HIV infection: Clinical manifestations and diagnosis", section on 'Diagnostic test performance in early HIV infection'.)
Strategies for screening and management of HIV during pregnancy to prevent perinatal transmission of HIV are discussed separately:
●(See "Screening and diagnostic testing for HIV infection in adults".)
●(See "Prenatal care: Initial assessment", section on 'HIV'.)
●(See "Prenatal evaluation of women with HIV in resource-abundant settings".)
●(See "Intrapartum and postpartum management of pregnant women with HIV in resource-abundant settings".)
●(See "Prevention of vertical HIV transmission in resource-limited settings".)
●(See "Prevention of HIV transmission during breastfeeding in resource-limited settings".)
WHY ANTIGEN/ANTIBODY TESTING IS NOT USED FOR HIV DIAGNOSIS IN INFANCY —
The diagnosis of human immunodeficiency virus (HIV) infection in infants and young children differs from that in adults and older children because antibody-only and antigen/antibody combination assays (that are generally used to diagnose HIV in adults and older children) will detect transplacentally transferred maternal HIV antibodies that persist for many months in infants [3,4]. In a study of 234 uninfected children born to mothers with HIV who were followed for up to two years, the mean age of loss of maternal antibody was 10.3 months; one child did not lose maternal antibody until >18 months of age [3].
To identify HIV infection in children <18 months of age, HIV virologic testing must be performed using assays that detect HIV deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), collectively referred to as "nucleic acid tests" (NATs) [5,6]. The choice of test is generally decided based on local availability. HIV-1 qualitative or quantitative RNA testing is used for infant diagnosis in most resource-abundant settings; however, HIV-1 qualitative DNA testing is a reasonable alternative if RNA testing is not available. Cord blood should not be used for testing, because of the possibility of contamination of the sample with maternal blood. Scheduled repeated testing is necessary because test sensitivity increases with time from HIV virus exposure and very recent infection may not be detected (table 1).
APPROACH TO PERINATAL HIV DIAGNOSIS —
The approach to the diagnosis of human immunodeficiency virus (HIV) in infants and children younger than 18 months of age depends on whether the HIV status of the mother is known [7]. The following recommendations for establishing the diagnosis of HIV infection in infants and young children are based on the guidelines of the United States Department of Health and Human Services (HHS), the National Institutes of Health (NIH), and the American Academy of Pediatrics (AAP) [5,7,8]. These guidelines also outline standard procedures for obtaining consent and for counseling. Clinicians managing these patients should also consider consulting a pediatric HIV expert or the Perinatal HIV/AIDS consultation line (888-448-8765) at the UCSF National Clinician Consultation Center for additional guidance.
Mother with HIV — In an infant born to a mother with HIV, serial testing is performed with a nucleic acid test (NAT) [5] (see 'Diagnostic tests' below). Infants born to individuals with HIV-2 infection should be tested with HIV-2-specific NATs performed at time points similar to those used for HIV-1 testing (see 'HIV-2 testing' below). Timing of testing depends upon whether the infant's risk for HIV acquisition is categorized as low or high risk, based on factors including maternal prenatal care and the timing of viral suppression (table 1).
Non-breastfed infants
●High risk – Infants at higher risk of perinatal transmission include those born to mothers with HIV who [5]:
•Had viremia (HIV RNA ≥50 copies/mL) after 20 weeks gestation
•Had acute or recent HIV acquisition during pregnancy
•Were diagnosed with HIV in labor or postpartum
For higher-risk infants, testing should be performed at birth, 14 to 21 days after birth, one to two months of age, two to three months of age (which usually corresponds to two to six weeks after the completion of presumptive HIV therapy), and four to six months of age (table 1). A positive result at any point should be confirmed as soon as possible with a repeat NAT.
The rationale for additional testing in high-risk infants is as follows:
•Testing at birth – Testing at birth allows early HIV diagnosis and initiation of ART. It also permits determination of timing of the infection if the infant is infected. A positive result at ≤48 hours after birth reflects HIV infection in utero, while infants who have a negative test result during the first week of life and subsequently have positive test results are considered to have intrapartum infection.
•Testing two to six weeks after cessation of antiviral prophylaxis – Antiviral prophylaxis, particularly combination ART, may reduce the sensitivity of testing during prophylaxis. Rather than deferring the earlier testing (at four to eight weeks of age) until after prophylaxis is discontinued (ie, 8 to 12 weeks of age), a strategy of testing at both time points allows prompt recognition of infected infants and may capture additional cases.
Recommendations for serial testing between birth and four to six months of age allow for diagnostic testing to be done after cessation of antiretroviral (ARV) prophylaxis for infants receiving combination ARV infant prophylaxis if the results of testing were negative while the infant was receiving prophylaxis.
●Low risk – Infants born to mothers with HIV with sustained viral suppression (defined as <50 copies/mL on at least two consecutive tests obtained at least four weeks apart) after 20 weeks gestation are at low risk of acquiring HIV.
For low-risk infants, testing is performed at birth, 14 to 21 days after birth, one to two months of age, and four to six months of age [5] (table 1). Testing at birth is not necessary for infants at low risk that are not being breastfed but may be done if there are concerns that the newborn could be lost to follow-up and not receive further testing.
A positive result at any point should be confirmed as soon as possible with a repeat NAT.
Breastfed infants — Many mothers with HIV choose to breastfeed their infants and in resource-limited settings, exclusive breastfeeding for the first six months is recommended for infants born to mothers with HIV. Infants who are breastfed by mothers with HIV are at risk of HIV acquisition due to ongoing potential exposure to HIV through breastmilk. Information on the risks, benefits, and details on how to minimize risk of HIV transmission during breastfeeding are discussed separately. (See "Intrapartum and postpartum management of pregnant women with HIV in resource-abundant settings", section on 'Breastfeeding' and "Prevention of HIV transmission during breastfeeding in resource-limited settings".)
Infants born to mothers with HIV who opt to breastfeed after comprehensive counseling should be supported and closely monitored. Testing should proceed according to the high-risk testing schedule (table 1), including an additional virologic test between the one to two month and four to six month time points if the gap between tests is greater than three months. We continue testing at least every three months throughout breastfeeding, followed by testing at four to six weeks, three months, and six months after cessation of breastfeeding [5]. A positive result at any point should be confirmed as soon as possible with a repeat NAT.
Maternal HIV status unknown — Ideally, all women should be tested to identify HIV infection either prior to pregnancy or early in the prenatal course. Recommendations for HIV screening during pregnancy and in the general adult population are discussed in separate topics. (See "Prenatal care: Initial assessment", section on 'HIV' and "Screening and diagnostic testing for HIV infection in adults", section on 'Routine screening'.)
If a woman presents in labor or at delivery without documentation of HIV status, expedited HIV testing should be performed with an HIV antibody or antigen/antibody combination immunoassay on either the mother and/or infant to determine HIV status in the mother. A positive result in the mother supports a diagnosis of HIV and must be confirmed. If serologic testing for HIV in the infant is positive, testing of the infant using NAT should proceed as described above to determine the status of the infant. (See 'Mother with HIV' above.)
It is important that testing in the peripartum period be expedited so that intravenous zidovudine can be given to the mother during labor and an appropriate antiretroviral regimen can be given to the newborn as soon as possible, ideally within six hours of birth.
APPROACH TO NONPERINATAL EXPOSURES —
Nonperinatal routes of human immunodeficiency virus (HIV) transmission in infants and children include premasticated feeding, sexual abuse, transfusion with contaminated blood products, and needlestick or contact with contaminated needles. In these circumstances, testing is recommended regardless of the presence of signs and/or symptoms of HIV infection. When HIV testing is performed in children of any age with HIV exposure from one of these routes, initial testing should be performed with an HIV antibody or antigen/antibody combination immunoassay. If positive, testing with nucleic acid test (NAT) is required to establish the presence of HIV in the infant, as described above. (See 'Why antigen/antibody testing is not used for HIV diagnosis in infancy' above and 'Diagnostic tests' below and "Screening and diagnostic testing for HIV infection in adults", section on 'Overview of available tests'.)
Additional monitoring, including serial HIV testing, may be necessary. In addition, post-exposure prophylaxis may be warranted, depending on the nature of the exposure. Additional information on post-exposure prophylaxis can be found on the Centers for Disease Control and Prevention website.
HIV testing is also appropriate for infants and children with signs and/or symptoms of HIV, even in the absence of documented or suspected HIV exposure.
INTERPRETATION OF DIAGNOSTIC TESTS —
Interpretation of human immunodeficiency virus (HIV) diagnostic tests in children <18 months of age differ from that in adults and older children.
Positive or indeterminate test result — A positive nucleic acid test (NAT) test at any point should be repeated as soon as possible. If the child has two positive NAT results at any point in time, the diagnosis of HIV is confirmed.
Infants with confirmed HIV infection should be managed by, or in consultation with, a clinician with expertise in pediatric HIV infection. The HIV/AIDS Management Clinician Consultation Center is an excellent resource for telephone consultation. The Center can be contacted at 1-800-933-3413, 9 am to 8 pm ET, Monday through Friday. The details of antiretroviral therapy (ART) for pediatric HIV infection are beyond the scope of this topic review. Guidelines on the treatment of pediatric HIV infection are available through the HIV.gov Clinical Info website. (See 'Society guideline links' below.)
Infants with a NAT result that falls in an indeterminate range (also called "weakly positive") should have the test repeated as soon as possible. In a systemic review and meta-analysis of 32 studies, indeterminate results accounted for 17 percent of initial non-negative test results, of which three-quarters were negative on repeat testing [9]. These findings highlight the importance of prompt, repeat testing following an indeterminate, weakly positive or positive NAT result in infants born to mothers with HIV.
Negative test result — A single negative NAT test result by itself does not definitively exclude HIV infection. Children with perinatal HIV exposure are deemed to have "indeterminate HIV infection" status until HIV infection is confirmed or excluded (see below) and should receive ARV regimens as appropriate for their age and risk for exposure. (See "Pediatric HIV infection: Management of infants born to mothers with HIV in resource-abundant settings", section on 'Approach to ARV drug management'.)
Children are not considered to be definitively negative for HIV infection until they have met specific criteria. Children with negative HIV tests that do not meet all criteria for definitive exclusion of HIV are considered to be presumptively not infected with HIV.
To presumptively exclude HIV infection, the child needs to meet all of the following criteria [5]:
●No clinical signs or symptoms consistent with HIV, including relevant opportunistic infections or low CD4 T cell count/percentage
●A series of negative HIV tests, depending on whether the infant is breastfed or not:
•For non-breastfed infants, one of the following negative HIV test results:
- Two or more negative NATs (one obtained at age ≥14 days and one at age ≥4 weeks), or
- One negative NAT at age ≥8 weeks (and at least two weeks after discontinuing multi-drug antiretroviral prophylaxis or presumptive therapy), or
- One negative HIV antibody test at age ≥6 months
•For breastfeeding infants, negative HIV test results at each of the following times during breastfeeding will confirm that the child remains presumptively uninfected:
- Two or more negative NATs (one obtained at age ≥14 to 21 days and one at age 4 to 8 weeks)
- Four to six months (with an additional test between the 1 to 2 and 4-to-6-month tests if the interval is longer than 3 months)
- Every 3 months during breastfeeding
To definitively exclude HIV infection, the child needs to meet all of the following criteria [5]:
●No clinical signs or symptoms consistent with HIV, including relevant opportunistic infections or low CD4 T cell count/percentage
●A series of negative HIV tests, depending on whether the infant is breastfed or not:
•For non-breastfed infants, one of the following negative HIV test results:
-Two or more negative NATs (one obtained at ≥1 month of age [and at least two to six weeks after discontinuing multidrug antiretroviral [ARV] prophylaxis or presumptive therapy] and one at ≥4 months of age), or
-Two negative antibody tests from separate specimens obtained at ≥6 months of age
•For infants that have discontinued breastfeeding, negative HIV test results at all time points including at each of the following times post cessation of breastfeeding:
-4 to 6 weeks
-3 months, and
-6 months (the final six-month test is considered the final outcome)
Children who are still breastfeeding cannot have HIV infection definitively excluded because they still have potential ongoing exposure to HIV through breastmilk. These children need to meet the criteria discussed above for definitively excluding HIV infection once they are no longer breastfeeding.
Additional HIV testing is not routinely required for non-breastfed infants who meet the criteria for definitive exclusion of HIV and who have had no known or suspected HIV exposure after birth. In the past, some experts would obtain a follow-up antibody test at 18 to 24 months of age to document seroreversion or clearance of maternal antibody and confirm the child's HIV-negative status, but this is not necessary [5,10-12].
DIAGNOSTIC TESTS —
Tests for the diagnosis of human immunodeficiency virus (HIV) in children younger than 18 months consists of DNA or RNA testing, both of which are considered nucleic acid tests (NATs).
HIV DNA assays — A qualitative HIV-1 DNA polymerase chain reaction (PCR) assay that detects HIV proviral DNA within peripheral blood mononuclear cells has been the primary test used for the diagnosis of HIV-1 infection in infants born to mothers with HIV [7,8]. Whole-blood specimens or dried blood spot samples may be used for testing. The test should be positive in infants infected with HIV even while they are being treated with antiretroviral therapy (ART).
DNA PCR testing will not detect very recent infection. The sensitivity of HIV-1 DNA PCR testing when performed at birth is 55 percent and increases to >90 percent by two to four weeks of age and 100 percent at three and six months [13-15]. The specificity of HIV-1 DNA PCR is 99.8 percent at birth and 100 percent at one, three, and six months.
Although historically HIV DNA PCR assays may have been less sensitive in detecting non-B subtypes of HIV [16-18], newer HIV-1 qualitative DNA PCR assays have good sensitivity against various subtypes of HIV [19]. HIV subtype B is the predominant viral strain in the United States. Non-subtype-B strains are more prevalent in other parts of the world. For example, subtype C predominates in Africa and India and subtype E in Southeast Asia.
HIV RNA assays — There are a variety of methodologies used to detect HIV RNA including reverse-transcription PCR, b-DNA, transcription-mediated amplification, and nucleic acid sequence-based amplification. Quantitative RNA assays are generally used as the standard viral load test performed for monitoring the response to treatment of HIV infection, but may also be used as a diagnostic assay for HIV infection in infants.
Compared with DNA PCRs, RNA assays may better detect HIV infection at birth, enabling the early initiation of ART [20], which has been shown to reduce infant morbidity and mortality. Studies have suggested that the sensitivity and specificity of qualitative and quantitative HIV RNA assays for identifying neonatal HIV infection are at least as good as those of HIV DNA testing [13-15,19,21,22]. However, false negatives can occur if either mother or infant are receiving treatment with ART [23].
The available HIV-1 RNA assays are capable of sensitive detection of all major HIV-1 subtypes. (See "Techniques and interpretation of HIV-1 RNA quantitation", section on 'Ability to detect different HIV-1 subtypes'.)
HIV-2 testing — Infants born to mothers with HIV-2 infection should be tested with HIV-2-specific NATs performed at time points similar to those used for HIV-1 testing. HIV-2 DNA PCR testing can be arranged by the HIV surveillance program of the state or local health department through their public health laboratory or the Centers for Disease Control and Prevention (CDC) because this assay is not commercially available [5]. (See "Clinical manifestations and diagnosis of HIV-2 infection", section on 'Testing for HIV-2 infection'.)
Other tests — Other tests used to detect HIV viral infection are not recommended in infants and young children:
●HIV-1 peripheral blood cell culture is not recommended, as it is expensive, it is not widely available, and results take a long time (up to four weeks) to become available [5,7,8,24].
●HIV-1 p24 antigen assays are not recommended in the United States, as they have lower sensitivity compared with other available assays for detecting HIV in infants <6 months of age [5,8].
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: HIV infection in infants and children".)
SUMMARY AND RECOMMENDATIONS
●Choice of test for HIV diagnosis in children younger than 18 months – In children <18 months born to a mother with human immunodeficiency virus (HIV), serial HIV testing is performed with either an RNA or a DNA nucleic acid test (NAT), rather than the antibody or antigen/antibody combination assays that are typically used for diagnosis in adults and older children. This difference in diagnostic tests is because the antibody tests will detect transplacentally transferred maternal HIV antibodies that can persist for many months in infants and cause false positive results. (See 'Why antigen/antibody testing is not used for HIV diagnosis in infancy' above.)
●Approach to perinatal HIV diagnosis
•Infants born to mothers with HIV – Infants born to mothers with HIV require serial HIV testing with NATs. The recommended schedule for virologic testing is summarized in the table (table 1). A positive result at any point should be confirmed as soon as possible with a repeat NAT. (See 'Mother with HIV' above.)
•Unknown maternal HIV status – If the maternal HIV status is unknown, serologic testing for HIV should be performed on the mother or infant. If the serologic test is positive, proceed with testing the infant with NAT in the same manner as for the infant of a mother with HIV. (See 'Maternal HIV status unknown' above.)
●Approach to non-perinatal exposures – When HIV testing is performed in children of any age with non-perinatal HIV exposure, initial testing should be performed with an HIV antibody or antigen/antibody combination immunoassay. If positive, testing with NAT is required to establish the presence of HIV in the infant. (See 'Approach to nonperinatal exposures' above and 'Why antigen/antibody testing is not used for HIV diagnosis in infancy' above.)
●Interpreting a positive HIV test result – A positive NAT test at any point should be repeated as soon as possible. If the child has two positive NAT results at any point in time, the diagnosis of HIV is confirmed. (See 'Positive or indeterminate test result' above.)
●Interpreting a negative HIV test result – A series of negative HIV test results is required to definitively exclude a diagnosis of HIV in a young child with perinatal exposure to HIV. Prior to definitive exclusion, children may have a presumptive exclusion of HIV based on initial testing results. Criteria to presumptively and definitively exclude HIV infection are outlined in the topic text. (See 'Negative test result' above.)
Children who are still breastfeeding cannot be definitively confirmed not to have HIV infection because they still have potential ongoing exposure to HIV through breastmilk. These children need to meet the criteria discussed above for definitively excluding HIV infection once they are no longer breastfeeding. (See 'Negative test result' above.)
ACKNOWLEDGMENT —
The UpToDate editorial staff acknowledges Heidi Schwarzwald, MD, MPH, who contributed to an earlier version of this topic review.
