g logo nhs blue


This Guidelines summary highlights the key points for primary care. Please see the full guideline for further information on:

  • laboratory surveillance
  • international surveillance
  • assessing susceptibility
  • urgent IgG testing of contacts
  • acute hospital settings
  • educational settings
  • international travel.

This summary has been abridged for print. View the full summary at guidelines.co.uk/453533.article.

Clinical presentation of primary measles infection

  • Measles starts with a 2–4 day illness (‘prodromal phase’) before the rash appears, which typically includes high fever, coryzal symptoms, cough and conjunctivitis. The latter is a more specific symptom that differentiates measles from many other causes of influenza-like illness. Symptoms typically peak on the first day of the rash
  • Fever typically increases during the prodromal phase, peaks (generally >39° C) around the rash onset, and will gradually decrease after that
  • The maculopapular rash generally starts on the face and behind the ears. The number of lesions/spots generally increase in the first 2–3 days, and their distribution expands further to the face, trunk, and can sometimes be generalised. Lesions can become confluent, particularly on the face and the trunk. The rash is red, blotchy, maculopapular (i.e. non-vesicular), not itchy, and generally lasts for 3–7 days, fading gradually
  • Koplik spots may appear around the time of the rash, sometimes one day before, and last for 2–3 days after the rash appears. These are small spots with white or bluish-white lesions, of about 2–3 mm in diameter, on an erythematous base on the buccal mucosa. These can be confused with other lesions in the mouth and therefore their suspected presence is an unreliable marker for measles
  • Several other common rash illnesses have a similar clinical presentation, including roseola (HHV6 infection), fifth disease (parvovirus B19 infection) and scarlet fever and therefore identification based on clinical features alone, particularly in children, is often unreliable. The timing and nature of symptoms is often helpful in the differential diagnosis. For example, while symptoms, including fever, peak with the onset of rash in measles; in roseola, the onset of rash generally coincides with clinical improvement. See the full guideline for a summary of the clinical features of each of these conditions

Breakthrough measles (reinfection)

  • The term ‘breakthrough measles’ (previously referred to as ‘reinfection’) is used to describe a confirmed case of measles in someone who developed immunity to measles, either from natural measles or from prior receipt of measles containing vaccine
  • Cases of breakthrough measles are generally mild, have a shorter duration and may not have the full triad of cough, coryza and conjunctivitis. In some cases of breakthrough measles a typical rash may not be observed
  • The immunological characteristics of breakthrough measles differ from those of primary vaccine failure, which is thought to occur when patients never develop immunity, for example when measles vaccine is given in the presence of maternal antibody. In contrast, breakthrough measles cases are thought to arise when antibody levels from past immunity wane, usually after many years, and subsequent close exposure can lead to measles viral replication and a consistent illness
  • Breakthrough measles cases are usually seen in patients who have received 2 doses of measles-containing vaccine, and antibody testing may be misinterpreted. The infectivity of these cases is lower than in primary measles infection, and transmission from breakthrough measles is rare

Complications of primary measles infection

  • The most frequent complications include viral pneumonitis and otitis media, as well as diarrhoea. Measles infection often leads to a temporary reduction in immune responses in the few weeks following infection, which may increase the risk of severe secondary bacterial and viral infections. Tracheobronchitis (‘measles croup’) and pneumonia due to secondary bacterial infection are frequent complications of measles
  • Encephalitis occurs more rarely, in about 0.05% to 0.1% of measles cases
  • Subacute sclerosing panencephalitis (SSPE) is a very rare but very severe complication, occurring in about 0.01% of cases
  • Immunosuppressed individuals are at higher risk than immunocompetent individuals of developing prolonged and severe measles, and of suffering complications
  • Measles can be particularly debilitating in very young infants and adults, who are more likely to develop complications and require hospitalisation. Measles can be severe in pregnant women and leads to an increased risk of prematurity and foetal loss, although there is no evidence that it leads to congenital defects. Young infants are at high risk of complications such as pneumonia, otitis media, and SSPE and of a fatal outcome

Transmission of primary measles

  • Any patient with suspected measles should be advised to avoid contact with immunosuppressed individuals and other vulnerable people (such as pregnant women and infants)
  • Individuals with primary measles infection are infectious from about 4 days before rash onset until 4 full days after the rash appears. Generally, secondary transmission is higher among close contacts, such as household members and non-household members with whom prolonged contact has occurred—such as students in the same classroom

Epidemiological parameters

  • A good understanding of the transmission parameters of measles is important to undertake an appropriate risk assessment
  • The incubation period is typically around 10–12 days from exposure to onset of symptoms, but can vary from 7 to 21 days
  • The period of infectiousness generally starts from about 4 days before the rash and lasts up to 4 days after the onset of rash
  • The transmission route of measles is mostly airborne by droplet spread or direct contact with nasal or throat secretions of infected persons. Much less commonly, measles may be transmitted by articles freshly soiled with nose and throat secretions, or through airborne transmission with no known face-to-face contact
  • Measles is extremely infectious, with a basic reproduction number (R0) estimated around 15–20 (i.e. on average, there will be 15–20 individuals infected from a single case in a totally susceptible population). The secondary attack rate is highest among close unimmunised contacts, particularly household contacts
  • The vaccine effectiveness of a single dose of MMR (mumps, measles, rubella) is around 90% and approximately 95% for two doses. Although vaccine failure is rare, it can occur, particularly after a single dose. In settings with high rates of close interpersonal contacts, such as large households or school settings, controlling measles outbreaks requires a high coverage of 2 doses of MMR

Surveillance of measles

  • Measles is a notifiable disease under the Health Protection Legislation (England) guidance 2010. Health protection teams should work with local partners to raise awareness of measles among health professionals in order to facilitate early recognition, diagnosis and reporting. Notification of the local health protection team (HPT) fulfils the physician’s responsibility to notify the local authority proper officer. Physicians managing the case should inform the HPT by phone as soon as is reasonably practical

Types of sample

Oral fluid (OF)

  • OF is the optimal sample for measles surveillance and should be taken from all suspected cases regardless of any other samples that may have already been taken, including when other laboratory methods have not confirmed measles
  • Testing for IgM on OF is more sensitive and more specific than serum, particularly in the first few days after the rash, as IgM antibodies are positive in >50% of samples on day 1 of the rash, and in over 90% by day 3 of the rash. For OF samples taken within 7 days of onset of disease, the virus reference department (VRD) also performs PCR analysis for RNA detection
  • OF is not appropriate to assess the immune status of contacts, for which serum should be tested instead


  • Serum samples can be used for IgM/IgG detection through enzyme immunoassays
  • Serum is the most appropriate sample to assess the immune status of contacts
  • Serum samples may still be IgM negative within 3 days of onset of rash
  • Serum can be used to confirm breakthrough measles (reinfection) by detection of high avidity measles IgG
  • Serum is not suitable for polymerase chain reaction (PCR) detection and viral typing
  • Serum cannot be used to distinguish wild-type measles from vaccine-derived measles following recent vaccination

Mouth swabs

  • Can be used for PCR if collected within 6 days of the onset of rash. However, a negative PCR result does not exclude a diagnosis of measles

Throat swabs/nasopharyngeal aspirate/urine/EDTA blood

  • Such samples can be used for PCR if collected within 6 days of the onset of rash, however they are less suitable than other sample types and are generally not advisable for measles testing

Collection of samples

  • Kits for collecting OF samples are available through the local PHE HPT. It is important that the sample is collected according to the instructions
  • The swab needs to be rubbed along the gum line for two minutes
  • If young children chew on the swab whilst the sample is being collected it should not compromise the sample collection. Sputum samples are not suitable for testing
  • Oral fluid samples sent for measles IgM testing are also tested for total IgG as an indication of whether the sample is suitable for testing. If the total IgG is less than 1 mg/L then this indicates a poor quality sample and the test may need to be repeated. If OF collection kits are not available then a serum sample PLUS mouth swab can be taken instead (and sent to VRD). A serum or OF sample is required for distinguishing a primary infection from breakthrough measles (reinfection)

Laboratory definitions

  • Laboratory confirmed case of measles: a suspected case with evidence of laboratory confirmation of acute measles infection (i.e. measles IgM in blood or OF in the absence of recent vaccination, or confirmed wild-type measles RNA in any clinical specimen)
  • Presumed primary infection: a laboratory confirmed case with no evidence of two doses of measles containing vaccine
  • Presumed breakthrough measles (reinfection): 

    detection of measles virus RNA in a suspected case of measles with mild / atypical symptoms and a reliable history of having received 2 doses of measles containing vaccine. Breakthrough measles can be confirmed by detection of high avidity measles IgG in serum or high levels of measles specific IgG in oral fluid. Measles IgM in serum may be negative

Public health management

  • The management of the index case and their contacts, based on the initial assessment, is described in figure 1 of the full guideline. For accurate exclusion of measles an OF sample should always be requested, an OF kit sent to the patient or their GP, and a sample sent back to VRD regardless of any local test results. The specimen should be taken as soon as possible and up to 6 weeks after the onset of rash. All samples from cases testing positive at a local laboratory should be forwarded to VRD for confirmation and further characterisation

Assessment of the index case

  • When measles is not endemic, the positive predictive value of a clinical diagnosis is generally poor. In the absence of laboratory results, the likelihood of measles will therefore depend upon an assessment of the epidemiological features
  • Case management should commence on the basis of this assessment, without waiting for the results of laboratory testing (even when requested urgently). Public health professionals should advise, as needed, on the use of appropriate laboratory samples for testing, at the right time, to reduce the likelihood of false negative results

Management definitions

  • Each case should be promptly investigated and classified according to laboratoryresults, clinical features and epidemiological features. For each reported case, the classification may change as more information (e.g. on the epidemiology or laboratory results) becomes available. The distinction between likely and unlikely is a qualitative judgement based on the overall picture, rather than presence or absence of a specific number of criteria

Categories are defined as:

  • Laboratory confirmed case of measles: A suspected case with laboratory confirmation of acute infection
  • Epidemiologically confirmed case of measles: A suspected case of measles who has a direct epidemiological link to a confirmed case of measles (i.e. where the onset of symptoms occurred within 7–21 days of exposure), or related to another epidemiologically confirmed case (e.g. in an outbreak setting)
  • Likely case of measles: A clinically typical case (see Table 1) of measles with epidemiological features that either increase the likelihood of the patient having been exposed and/or favour the diagnosis of measles relative to other causes of rash illness. Epidemiological factors for risk assessment are summarised in Table 1

Table 1: Clinical features of measles



  • Fever >39ºC in the absence of antipyretics

  • Generalised maculopapular rash

  • Conjunctivitis

  • Cough and/or coryza

  • Generally very unwell


  • Generally milder illness

  • Fever typically 37.5–39ºC

  • Rash may be more localised

  • May not have conjunctivitis or cough


  • Any other presentation

  • Likely breakthrough measles (reinfection): a suspected case of measles with mild or atypical symptoms (see Table 1) and epidemiological features that increase the likelihood of the patient having been exposed to measles in a patient who has a documented history of two doses of measles containing vaccine and/or is known to be measles IgG positive from previous testing
  • Unlikely case of measles: A suspected case of measles which does not meet the definition of a likely case, either because it is clinically atypical (see Table 1) or because the epidemiological context is not suggestive of measles

Patient information required for assessment of suspected measles cases

Demographic details

  • Name
  • Sex
  • Date of birth
  • Address
  • NHS number
  • Contact details

Clinical and laboratory features

  • Signs and symptoms: collect information on signs and symptoms, and importantly the onset dates of rash
  • Laboratory results: document the type of tests conducted and results

Individual epidemiological features

  • Travel: any travel within and outside the UK during the incubation period, with an assessment of whether travel was in an area where measles is known to be circulating
  • Ethnic and cultural/religious background: obtain details on the patient’s ethnicity, and importantly, assess whether the patient is a member of an under-vaccinated population group (e.g. Charedi Orthodox Jewish community, Steiner community)
  • Immunisation history: any known vaccination history or history of measles. If not known, ask where the patient was born and grew up to help assess the likelihood of vaccination and/or natural exposure
  • Epidemiological link: assess if there has been a known epidemiological link with another laboratory or epidemiologically confirmed case
  • Generally, epidemiological information is a better predictor of measles than the clinical features. Given the implications of an incorrect classification, it is recommended that classification for management should be undertaken by or discussed with an experienced member of the Health Protection Team.

Factors to consider in the risk assessment

Factors increasing the risk of exposure

  • Membership of a community known to be more susceptible e.g. traveller community, Charedi Orthodox Jewish community, anthroposophic (Steiner) communities, local community with low MMR vaccination coverage
  • Visited an area (local or international) where measles is known to be circulating, during the incubation period
  • Attendance at large international mass gathering events, where substantial mixing occurs between individuals potentially travelling from areas where measles is circulating. This would include events such as music festivals etc.

Factors favouring the diagnosis of primary measles infection

  • Age: the likelihood of a suspected case being confirmed as measles is higher among adolescent and young adults. In infants and toddlers, measles-like clinical presentations due to other illnesses, such as roseola or scarlet fever, are common
  • A lack of immunity or incomplete vaccination: The diagnosis is more likely if cases are unvaccinated or partially vaccinated, and have no prior history of measles infection
  • Regardless of any other testing performed, all cases should have OF samples taken and sent to VRD for exclusion/confirmation of the diagnosis

Management of contacts

Identification of contacts

  • The best way to protect individuals and to achieve measles elimination is with high vaccination coverage with two doses of MMR vaccine (≥95%)
  • Where practicable, all contacts should be provided with information on symptoms of measles and advised to exclude themselves from schools or other settings if they develop symptoms
  • Although post exposure prophylaxis is of limited effectiveness, there may be an opportunity to offer some protection to exposed vulnerable contacts. This requires identification of contacts in the following order of priority:
  1. Immunosuppressed contacts
  2. Pregnant women and infants <12 months
  3. Health care workers
  4. Healthy contacts

Defined contacts

  • Generally, secondary transmission is higher among close contacts, such as members of a household or individuals who have close contact with each other over a long period of time, or students in the same classroom
  • Contact tracing should focus primarily on:
    • close contacts including household contact
    • face to face contact of any length
    • more than 15 minutes in a small confined area e.g. room in a house, classroom, 4 bed hospital bay

Poorly defined contacts

  • There will often be situations where a number of individuals may have been exposed in a shared setting e.g. hospital A&E or GP waiting area, where the level of contact is unclear
  • When the information provided cannot clearly define the level of contact but there are known immunosuppressed individuals involved, these should be managed as close contacts and rapidly assessed for post-exposure prophylaxis
  • Where there is a defined list of contacts, but it is not clear if the group contains immunosuppressed individuals, an individual risk assessment is not practicable. In this situation, ‘warn and inform’ letters/messaging should be issued to all potential contacts (see the full guideline)
  • If there is no identifiable list of contacts at all, then other means of case-finding should be considered, such as writing to local healthcare providers, information leaflets/posters in public areas and  other communication activities as relevant to the setting

Defining the time window for receiving post-exposure prophylaxis

  • Immunocompetent cases are considered infectious from 4 days before to 4 days after the onset of rash with peak infectiousness occurring during the prodromal phase. Immunosuppressed individuals may be infectious for longer and may not display typical symptoms
  • For household contacts, or any contact with ongoing exposure during the episode of illness, the time window for receiving post exposure prophylaxis should be calculated from the date of onset of rash in the index case
  • For other contacts, the time window for receiving post exposure prophylaxis should be calculated from the last day of exposure. In most instances, susceptible contacts will have been exposed on a single day. However, if exposure has occurred over several days (e.g. a child attending nursery in the early prodromal phase) the time for receiving post exposure prophylaxis should be calculated from the last day of exposure to the infectious source

Post-exposure prophylaxis

  • Immunosuppressed, pregnant and infant contacts: Detailed recommendations for post-exposure prophylaxis of vulnerable contacts with immunoglobulin or MMR can be found in the PHE post-exposure prophylaxis guidelines
  • Other healthy contacts: MMR can be offered to any healthy contact who is unvaccinated or incompletely vaccinated and not likely to be immune
  • Individuals who develop symptoms within 10 days of receiving post-exposure vaccination should be assumed to have true measles unless the index case has been discarded. Oral fluid samples should be sent to VRD for confirmation and genotyping

Primary care settings

  • All staff working in health care settings with any contact with patients (including ambulance drivers, receptionists etc.), should have their immune status assessed and, if non-immune or unclear, offered MMR vaccination
  • Whenever possible, signs should be placed in GP surgery waiting areas advising patients with any rash illness to report to reception. Receptionists should know that any patients with fever and rash are potentially infectious and, ideally, should attend at the end of surgery to minimise the risk of transmission. Where patients with a fever and rash attend when other patients are in the waiting room, they should be directed to a side room
  • When a GP refers a suspected measles case to A&E/hospital they should inform the hospital staff ahead of time, so that the case can be appropriately isolated on arrival
  • When a likely case of measles is reported from a primary care setting, the HPT staff should advise about infection control measures and conduct a risk assessment. If the patient was not isolated, and for example, exposed other patients in the waiting room, then HPT staff should conduct a risk assessment as per current guidelines

Considerations for healthcare workers

  • All healthcare workers (including receptionists, ambulance workers etc.) should have satisfactory evidence of protection against measles to protect both themselves and their patients. Satisfactory evidence of protection includes documentation of having received two or more doses of measles containing vaccine and/or a positive measles IgG antibody test


  • An outbreak is defined as two or more epidemiologically linked cases that occur within one incubation period of each other (i.e. the second case occurs between 7 and 21 days of the first case)
  • While most outbreaks will occur within the household setting, an outbreak control team may need to be convened when transmission has occurred in other settings where a large number of people been exposed (e.g. school outbreak) or where the population exposed may be more vulnerable (e.g. hospital outbreak). If the reported number of measles cases across a local area or community is above the expected level, an outbreak control team should be considered to identify common factors and implement control measures
  • An appropriate outbreak control team is likely to include, if appropriate:
    • health protection specialist from the local HPT
    • screening and immunisation team representative
    • education representative from local authority (LA)
    • school nurse/team leader
    • GPs (if identifiable practices within community)
    • local director of public health or appropriate representatives
    • local clinical commissioning groups
    • communications leads (PHE, local authority to liaise as necessary)
    • acute trust representative (microbiologist, director of infection prevention and control; microbiologist (if different); infection control team/paediatric consultant/medical director, occupational health)

Planning and response

  • Health Protection Teams should work with their local NHS England Screening and Immunisation teams to ensure that the necessary resources are available within their area to manage outbreaks. HPTs should know where to access urgent laboratory testing services (particularly measles IgG) and human normal immunoglobulin (HNIG) supplies. Access to a small stock of MMR vaccine should be available by the next day, including at weekends, and HPTs should ensure they know which walk-in clinics or out of hours GP services are available at the weekend to enable prompt administration of MMR or HNIG if required
  • If an outbreak occurs in a school where vaccination coverage is known to be low, an urgent campaign should be considered. Vaccination of all susceptible students will limit the risk of tertiary transmission within the school setting. Commissioners should have contracts in place to provide support for vaccination campaigns in defined settings, such as schools, and providers should have arrangements in place to source MMR promptly for outbreak control


Full guideline:

Public Health England. National measles guidelines. London: Public Health England. Available from: www.gov.uk/government/publications/national-measles-guidelines.

Published date: November 2019.