Screening

Management of asymptomatic contacts

Monitor asymptomatic contacts of confirmed (or highly probable) cases for symptoms after their last exposure to the case. Guidelines for contact monitoring may vary between regions. Guidelines from the World Health Organization, the UK Health Security Agency, and the US Centers for Disease Control and Prevention are presented here. Consult your local public health authority for the most current guidance.

World Health Organization

The World Health Organization (WHO) defines a contact as a person who has been exposed to an infected person during the infectious period (i.e., the period beginning with the onset of the index case’s first symptoms, and ending when their skin lesions have crusted, the scabs have fallen off, and a fresh layer of skin has formed underneath) and has had one or more of the following exposures with a probable or confirmed case (including health workers potentially exposed in the absence of proper use of appropriate protective personal equipment [PPE]):[81] 

  • Direct skin-to-skin and skin-to-mucosal or mouth-to-mucosal physical contact (e.g., touching, hugging, kissing, intimate or sexual contact)

  • Contact with contaminated materials (e.g., clothing or bedding, including material dislodged from bedding or surfaces during handling of laundry or cleaning of contaminated rooms)

  • Prolonged face-to-face respiratory exposure in close proximity

  • Respiratory exposure or eye mucosal exposure to lesion material (e.g., scabs/crusts) from an infected person.

The WHO offers the following recommendations for asymptomatic contacts.[81]

  • Monitor asymptomatic contacts daily for the onset of signs and symptoms for a period of 21 days from the last contact with a probable or confirmed case (or their contaminated materials) during the infectious period. Contacts can be monitored passively (i.e., self monitoring), actively, or directly, depending on available resources. Contacts should monitor their temperature twice daily.

  • A contact who develops prodromal symptoms or lymphadenopathy without a rash should be isolated and closely examined for signs of a rash. The patient should be tested (oropharyngeal, anal/rectal swabs may be done if no skin/mucosal lesions). If the test is negative, the contact should continue to monitor for the signs of rash for the next 5 days. If no rash develops, the contact may return to temperature monitoring for the remainder of the 21 days. If the contact develops skin or mucosal lesions, they must be isolated and evaluated as a probable case. A specimen from the lesions should be collected for laboratory analysis.

  • Asymptomatic contacts that adequately and regularly monitor their status can continue routine daily activities (e.g., going to work, attending school) and no quarantine is necessary. Contacts of confirmed cases should avoid sexual contact with others for 21 days, irrespective of symptoms. Local health authorities may choose to advise pre-school children who have been exposed to a case not to attend daycare, nursery, or other group settings during the contact follow-up period.

  • Asymptomatic contacts should not donate blood, cells, tissue, organs, breast milk, or semen while they are under symptom surveillance.

  • Asymptomatic contacts should try to avoid physical contact with children, pregnant women, immunocompromised people, and animals (including pets).

  • Health workers with an occupational exposure should notify infection control, occupational health, and public health authorities to receive an assessment and management plan of the potential infection. Health workers who have unprotected exposure (i.e., not wearing appropriate PPE) to patients (or possibly contaminated materials) do not need to be excluded from work if they are asymptomatic, but should undergo active surveillance for symptoms and not work with vulnerable patients during this period. Follow local guidance.

  • Non-essential travel should be avoided.

For more detailed information, see the following guidance:

UK Health Security Agency

The UK Health Security Agency (UKHSA) recommends categorising contacts of confirmed (or highly probable) cases based on their exposure risk. As of 19 July 2022, close contacts no longer need to isolate at home for 21 days if they are asymptomatic.[195]

  • High risk (category 3): unprotected direct contact or high-risk environmental contact. The following public health advice is recommended for this group:

    • Passive monitoring

    • Avoid sexual or intimate contact and other activities involving skin-to-skin contact for 21 days from last exposure

    • Avoid contact with immunosuppressed people, pregnant women, or children <5 years of age, where possible, for 21 days from last exposure

    • Consider exclusion from work for 21 days following a risk assessment if work involves skin-to-skin contact with immunosuppressed people, pregnant women, or children <5 years of age (not limited to healthcare workers).

    • Contacts who are children do not require exclusion from school

    • International travel is not advisable.

  • Medium risk (category 2): unprotected exposure to infectious materials including droplet or airborne potential route. The following public health advice is recommended for this group:

    • Passive monitoring

    • Avoid sexual or intimate contact and other activities involving skin-to-skin contact for 21 days from last exposure

    • Contacts who are children do not require exclusion from school

    • International travel is not advisable.

  • Low risk (category 1): protected physical or droplet exposure (category 1B), or no physical contact or unlikely droplet exposure (category 1A).

    • There is no public health advice for this group.

For more detailed information, see the following guidance:

Centers for Disease Control and Prevention

The US Centers for Disease Control and Prevention (CDC) recommends categorising contacts based on their exposure risk.[196]

  • High degree of exposure: require monitoring for signs and symptoms for 21 days after last exposure. Post-exposure vaccination is recommended.

  • Intermediate degree of exposure: require monitoring for signs and symptoms for 21 days after last exposure. Post-exposure vaccination may be considered on an individual basis if the benefits outweigh the risks.

  • Lower degree of exposure: require monitoring for signs and symptoms for 21 days after last exposure. Post-exposure vaccination is not recommended.

  • No risk of exposure: no monitoring or post-exposure vaccination is recommended.

Contacts who remain asymptomatic can continue their routine daily activities. If symptoms develop, patients should self-isolate and contact their healthcare provider.

For more detailed information see the following guidance:

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