MERS-CoV: diagnostic testing

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Aim of guidance

This guidance supersedes guidance previously found in ‘Middle East Respiratory Syndrome Coronavirus (MERS-CoV)’.

It is aimed at clinicians and healthcare workers, health protection teams (HPTs) and clinical diagnostic laboratories in both the public and private sectors.

MERS-CoV reporting and diagnostics

Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic respiratory virus. It can be transmitted to humans through direct or indirect contact with infected dromedary camels or contaminated camel products. Human-to-human transmission does occur, through close unprotected contact with MERS-CoV positive cases in health care settings and among household members.

The WHO MERS dashboard maintains up-to-date MERS-CoV epidemiological case data.

The UK government is obligated to report any MERS-CoV positive cases to the World Health Organization (WHO) under the International Health Regulations (IHR) 2025 via the National IHR Focal Point. This guidance sets out the explicit testing and reporting criteria required by the NHS and the UK Health Security Agency (UKHSA) to meet these obligations. As a notifiable disease, Registered Medical Practitioners are required to notify all suspected cases of MERS urgently (within 24 hours) to a health protection team, under Health Protection (Notification) Regulations 2010 (HPNR).

Primary diagnostic testing for MERS-CoV is available at UKHSA and Collaborating NHS Regional Public Health Laboratories (PHLs) or may be offered by non-UKHSA-designated MERS-CoV (NHS/non-NHS) testing laboratories with adequately verified MERS-CoV assays holding appropriate accreditation. Confirmatory testing and characterisation for international reporting is performed in the National Reference Laboratory in the Respiratory Virus Unit (RVU), Colindale.

MERS-CoV viruses are genetically diverse and continuously evolving. Genomic surveillance at the animal interface is limited, and human cases are rare, with limited virus genome sharing. Consequently, this guidance takes into consideration associated uncertainties for diagnostics, including limited availability of contemporaneous virus positive materials for up-to-date diagnostic assurance.

UKHSA guidance is available on when to suspect a case of MERS-CoV, and the classification of contacts of MERS-CoV cases and follow-up advice.

Who to inform testing is taking place

The decision to test for MERS-CoV should be based upon the case definition and made after consultation with local NHS infection specialists and the local health protection team.

If testing is required, the local HPT and NHS infection specialists will provide advice on initial management of the case.

HPTs should inform the UKHSA Acute Respiratory Infections team when a MERS-CoV infection is suspected (via acute.respiratory@ukhsa.gov.uk), or phone the EEI duty consultant on-call, if out of hours.

Testing strategy for suspected MERS-CoV

Diagnostic testing for MERS-CoV should be undertaken for individuals according to the criteria described in MERS-CoV: diagnosis and management of cases and contacts - GOV.UK. The summary process is available as an algorithm.

UKHSA-designated PHLs offer MERS-CoV diagnostic testing for England. If the local NHS laboratory service offers an accredited MERS-CoV diagnostic test, samples may be processed there.

UKHSA-designated PHLs will only accept samples for testing where the patient meets the case definition or after discussion with the local clinician explaining the need for testing. If initial tests are negative for MERS-CoV and the patient develops new relevant symptoms within the 14 days following exposure, swabbing and testing should be repeated.

Sampling for diagnostic testing of MERS-CoV

Do not delay sampling and testing. Samples should be obtained and sent to a MERS testing laboratory as soon as possible after identifying the possibility of MERS-CoV infection and results should be available within 24 hours of sample receipt. In exceptional situations where out of hours testing may be necessary, discuss options with the local NHS testing laboratory or UKHSA PHL duty consultant virologist.

When taking samples ensure that you are wearing the required PPE. Further guidance can be found in the NHS National infection prevention control manual for England and the Addendum on HCID PPE. All samples must be labelled with the patient’s name, date of birth, NHS number, the date and anatomical site of the sample. Unlabelled samples cannot be processed.

After consultation with the HPT and/or consultant infection specialist, the clinical team should take the following samples specifically for MERS-CoV testing:

2 upper respiratory tract samples (box 1) (nasopharyngeal viral swabs are preferable, but nose and throat swabs are acceptable where supported by local validation, or nasopharyngeal aspirate)
the primary testing laboratory should use one sample for testing and store the second. The stored sample should be reserved for forwarding to RVU if a presumptive positive is detected and confirmation is needed. Ideally, the stored sample should be collected into virus transport medium (VTM), avoiding medium containing an inactivating agent
if obtainable and the patient’s symptoms or clinical assessment considers it appropriate, take a lower respiratory tract sample, 2 if feasible (box 1) (sputum, or an endotracheal tube aspirate if intubated), in addition to the upper respiratory tract samples. Avoid medium containing an inactivating agent

If the local NHS laboratory service offers an accredited MERS-CoV diagnostic test, samples may be processed there. If primary testing is unavailable locally, send all samples to a designated MERS testing UKHSA PHL for testing. Do not send samples directly to RVU Colindale for primary testing.

Additional samples should be collected if other diagnostic testing is required by the local laboratory.

Box 1

A single negative test result particularly if from an upper respiratory tract sample, may not exclude MERS-CoV in a patient with clinically relevant travel history and disease. Where clinical suspicion remains, repeat sampling including from the lower respiratory tract if possible is recommended. Lower respiratory tract samples obtained as soon as possible after symptom onset (less than 7 days) have the best diagnostic sensitivity. Studies have also shown shown that swabs taken from the nasopharynx not just the nostril have a better diagnostic sensitivity for MERS CoV. Not all NHS laboratories will have the capability to test lower respiratory tract samples for MERS-CoV. Clinicians should discuss options with the local NHS testing laboratory or UKHSA PHL duty consultant virologist.

As the clinical features of MERS-CoV are similar to those of other respiratory infections, consider testing for a wide range of respiratory pathogens, as this helps in determining a final cause for the illness, depending on the local epidemiology of circulating respiratory viruses and travel history.

What tests will be performed

The UKHSA-designated MERS testing PHL will use verified nucleic acid amplification tests for MERS-CoV and hold appropriate accreditation.

Laboratories that test for MERS-CoV can also perform seasonal respiratory virus screens if desired, but panels offered may vary. If a referring laboratory chooses to perform its own respiratory virus panel (in addition to requesting MERS-CoV testing), a local risk assessment should be performed for handling a suspected CL3 organism, and appropriate health and safety measures followed.

If alternate diagnoses are under consideration and any additional tests are required, please discuss with the PHL at the time of referral. Always inform each laboratory of the risk of infection with HG3/4 pathogens, prior to sending samples, and ensure request forms clearly state the HG3/4 risk

Non inactivated samples must be handled at CL3. Aliquots of the original sample should be separated and inactivated by lysis or other validated method. Following inactivation, sample aliquots may be handled at CL2 for molecular testing. It is important to reserve some (non-inactivated) material suitable for virus culture should it be required.

Transport of samples to UKHSA and Collaborating NHS Regional Public Health Laboratories for MERS-CoV diagnostic testing

Details of the address of each of the UKHSA and Collaborating NHS Regional Public Health Laboratories that offer testing for MERS-CoV are listed in Table 1 and on the public health laboratories website.

Send all samples for MERS-CoV primary testing to the PHL. Do not send any samples directly to RVU Colindale. The PHL will send samples to the RVU if required.

MERS-CoV is an Advisory Committee on Dangerous Pathogens (ACDP) Hazard Group 3 pathogen. Diagnostic samples should be sent by Category B transport (UN3373, packing instruction P650), clearly indicating that the samples contain a suspected HG3 pathogen on any referral form to ensure safe handling on receipt.

Provide the contact details for your clinical laboratory for the purposes of telephone and hard copy reporting. This must include an out-of-hours telephone number.

Send samples by DX transfer or courier services according to urgency and timing.

The referring laboratory is responsible for booking and paying for the transport.

MERS-CoV test result communication

Results from the UKHSA and Collaborating NHS PHLs should be provided within 24 hours of receipt of the sample at the testing laboratory.

PHL staff are responsible for informing the referring clinical centre, HPT and UKHSA acute respiratory infections team of the results including via urgent phone communication to the referring clinical centre.

If testing has taken place outside of a UKHSA-designated service, the testing service must inform the referring clinical centre, and the HPT of the results including via urgent phone communication to the referring clinical centre.

The relevant clinical team that requested the tests will need to be available to receive the results, which may be out of routine hours.

The laboratory testing process may generate negative, positive, or inconclusive results for the presence of MERS-CoV, as well as for the presence of other respiratory virus pathogens.

MERS-CoV testing results - definitions and actions for primary testing laboratories

MERS-CoV positive

If the NHS or PHL MERS testing laboratory obtains a presumptive positive result for MERS-CoV regardless of any other respiratory pathogen detection rapid communication is essential, so that public health control measures can be implemented. Refer to the MERS-CoV: diagnosis and management of cases and contacts.

The primary testing laboratory should contact RVU to arrange sending of samples for confirmatory testing in the event of a MERS-CoV presumptive positive result. See section on referral of presumptive positives to RVU for guidance on sample referral.

MERS-CoV negative

If the test results show that the sample was MERS-CoV negative, then the patient should be managed according to any other relevant test results.

If appropriate samples were obtained and an alternative diagnosis is likely, then MERS-CoV may be considered excluded. In cases where a strong clinical suspicion of MERS-CoV remains after a single negative test result, particularly if this is from an upper respiratory tract specimen, repeat sampling and testing, especially with lower respiratory specimens, is strongly recommended. For advice and to discuss options for further testing, the UKHSA PHL or NHS duty microbiologist or virologist should contact the RVU.

MERS-CoV testing inconclusive

Where inconclusive results are obtained, the patient should continue to be managed as a suspected MERS-CoV case, until a definitive result is obtained unless a clear alternative diagnosis has been made and dual pathology excluded.

Referral of presumptive positive MERS-CoV human samples to the Respiratory Virus Unit, Colindale

All presumptive positive MERS-CoV positive samples must be notified to RVU by telephone and arrangements made to send urgently for confirmatory testing and virus characterization including whole genome sequencing.

For cases where MERS-CoV testing was inconclusive, or where negative results have been obtained, but clinical suspicion remains, PHL or NHS laboratories should contact the RVU to discuss appropriate testing and sample referral.

To contact RVU Colindale within working hours (Monday to Friday, 09:00 to 17:00) telephone:

020 8327 7125
020 8327 7002
020 8327 6017

If managing out of hours, contact the Epidemic and Emerging Infections (EEI) duty consultant for advice.

After discussion with RVU, samples should be sent by category B transport, packaged accordingly, with clear labelling to indicate an urgent sample with suspected Hazard Group 3 pathogen. Routine daily DX transfer can be used (package separately from other samples) or specific courier services depending on urgency and timing.

The completed E16 MERS-CoV referral form must be included in the package.

All available original clinical samples collected for testing, including residual material from the tested sample and the second reserve sample, must be sent to RVU (minimum 400µl, in VTM, not lysed or inactivated). Non-inactivated material is important due to suitability for virus culture. In the event there is a lower volume, or no clinical material remains, contact RVU for further advice.

Reporting of confirmatory MERS-CoV results by the Respiratory Virus Unit

RVU will report all results of confirmatory testing, positive and negative, by phone to the referring laboratory.

The Acute Respiratory Infections Team should be notified by phone (followed up by email) in hours. Out of hours, notify the EEI duty consultant by phone. The local HPT will be updated by the ARI team if results are obtained during working hours, or by the EEI consultant outside of working hours.