Middle East Respiratory Syndrome (MERS) Vaccines
The emergence of the betacoronavirus which causes Middle East Respiratory Syndrome Coronavirus (MERS-CoV), a viral, often fatal, respiratory illness in humans is a zoonotic coronavirus, and the source of the virus remains unknown, says the U.S. CDC.
MERS-CoV was first reported in the Kingdom of Saudi Arabia in 2012. Human-to-human transmission is amplified among household contacts and in healthcare settings, stated the ECDC during September 2020. Scientific evidence suggests that people are infected through direct or indirect contact with infected dromedary camels. It causes severe infections that result in a high mortality rate, says the World Health Organization (WHO).
As of February 18, 2021, the CDC had not approved a MERS-CoV prevention vaccine.
MERS-COV Vaccine Candidates
VTP-500 (ChAdOx1) MERS-CoV is a vaccine candidate from the University of Oxford that consists of the replication-deficient simian adenovirus vector ChAdOx1, containing the MERS Spike protein antigen. The VTP-500 vaccine is administered alone both as a single administration and with a homologous prime-booster.
INO-4700 MERS-CoV is a DNA plasmid vaccine that expresses the MERS CoV spike (S) glycoprotein.
MVA MERS (Modified Vaccinia virus Ankara) is a vaccine candidate that contains the full-length spike gene of MERS-CoV.
MERS-CoV Vaccine Research News
February 1, 2021 - The WHO reported between June through December 31, 2020, the National IHR Focal Point of Saudi Arabia reported four additional cases of MERS-CoV with one associated death. The cases were reported from Riyadh (two cases), Taif (one case), and Al-Ahsaa (one case) Regions.
January 21, 2021 - VBI expects to initiate the first Phase 1/2 clinical study of VBI-2902 in Canada in Q1 2021. VBI-2901 is a trivalent pan-coronavirus vaccine candidate expressing the SARS-CoV-2 (COVID-19), SARS-CoV (SARS), and MERS-CoV (MERS) spike proteins. To support the Phase 1/2 studies, VBI was awarded up to CAD$56 million by the Strategic Innovation Fund of the Government of Canada, to be paid as retrospective reimbursement for eligible expenses.
January 11, 2021 - A non-peer-reviewed study, 'Immunogenicity and efficacy of the COVID-19 candidate vector vaccine MVA SARS 2 S in preclinical vaccination', used their earlier experience with the Middle East respiratory syndrome coronavirus, they engineered the MVA to express the full-length SARS-CoV-2 spike protein stably when serially amplified.
December 23, 2020 - The Lancet published the study: Safety and immunogenicity of INO-4800 DNA vaccine against SARS-CoV-2: A preliminary report of an open-label, Phase 1 clinical trial. INO-4800 demonstrated excellent safety and tolerability and was immunogenic in 100% (38/38) of the vaccinated subjects by eliciting either humoral or cellular immune responses.
December 20, 2020 - Study published by BMC: Coronavirus vaccine development: SARS and MERS to COVID-19. This study summarizes key takeaways from previous vaccination studies of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and the Middle East Respiratory Syndrome Coronavirus (MERS-CoV), highlighting the pros and cons of each immunization strategy.
December 9, 2020 - Research Article: An infectious cDNA clone of a growth attenuated Korean isolate of MERS coronavirus KNIH002 in clade B. The infectious clone for the KNIH002 in contemporary epidemic clade B would better understand a functional link between MERS-CoV's molecular evolution and pathophysiology by comparative studies with EMC strain.
November 19, 2020 - The Lancet published a systematic review and meta-analysis that provides comprehensive data on the viral dynamics of SARS-CoV-2, including the duration of RNA shedding and viable virus isolation. This study found SARS-CoV-2 viral load in the upper respiratory tract appeared to peak in the first week of illness, whereas that of SARS-CoV peaked at days 10–14 and that of MERS-CoV peaked at days 7–10.
November 16, 2020 - A new study challenged chickens, turkeys, ducks, quail, and geese with SARS-CoV-2 or MERS-CoV. We observed no disease and detected no virus replication and no serum antibodies. We concluded that poultry is unlikely to serve a role in the maintenance of either virus.
November 8, 2020 - The Kingdom of Saudi Arabia's Ministry of Health reported a MERS-CoV infection in a man from Riyadh who had contact with camels. The country's last MERS-CoV cases were reported in May 2020.
October 6, 2020 - The Lancet published a new study that concludes 'the need for an effective One Human-Environmental-Animal Health multidisciplinary consortium across Africa, Middle East, and Asia to tackle the ever-present threat of lethal coronaviruses and other emerging infections remains a global priority.
October 6, 2020 - A new study reported 'Zoonotic infection of dromedary-exposed individuals is taking place in Nigeria and suggests that the extent of MERS-CoV infections in Africa is underestimated. Therefore, MERS-CoV could adapt to human transmission in Africa rather than the Arabian Peninsula, where attention is currently focused.'
August 3, 2020 - Report: 3C-like protease inhibitors block coronavirus replication in vitro and improve MERS-CoV-infected mice's survival.
April 30, 2020 - A Middle East respiratory syndrome coronavirus vaccine candidate was shown to be safe, well-tolerated, and induced a robust immune response in a Phase 1 first-in-human clinical trial. Initial findings from the trial were published in The Lancet Infectious Diseases. The study, conducted at the Walter Reed Army Institute of Research Clinical Trials Center, evaluated a candidate DNA vaccine (GLS-5300) co-developed by GeneOne Life Science Inc. and Inovio Pharmaceuticals. Though other vaccine candidates have previously been tested for use in camels, which are the suspected source of the virus that causes MERS-CoV, this is the first vaccine candidate tested in humans.
April 20, 2020 - A MERS vaccine candidate was shown to be safe, well-tolerated, and induced a robust immune response in Phase 1 first-in-human clinical trial. Initial findings from the trial were published in The Lancet. The study, conducted at the Walter Reed Army Institute of Research Clinical Trials Center, evaluated a candidate DNA vaccine (GLS-5300) co-developed by GeneOne Life Science Inc. and Inovio Pharmaceuticals.
April 17, 2020 - Investigational chimp adenovirus MERS-CoV vaccine protects monkeys.
February 13, 2020 - Remdesivir prevents MERS coronavirus disease in monkeys.
February 5, 2020 - WHO overview of candidate vaccines' types/classes against MERS-CoV.
December 20, 2019 - Middle East respiratory syndrome coronavirus (MERS-CoV) overview published by the WHO.
MERS-CoV Cases - 2020
From 2012 through December 2020, a total of 2,566 laboratory-confirmed cases of MERS-CoV and 882 associated deaths were reported globally to the WHO under the International Health Regulations (IHR 2005).
The WHO's Eastern Mediterranean Regional Office reported the Kingdom of Saudi Arabia continues to perform extensive surveillance and testing for MERS-CoV. During the 3-year study period, the MoH tested >65,000 suspected MERS-CoV case-patients per year on average. Of these, 0.3% were found positive for MERS-CoV, reported the CDC, Volume 26, Number 7—July 2020.
In 2020, 77% of the 57 cases in Saudi Arabia were reported in Riyad (25), Asir (7), Eastern Province (6), and Makkah (6). On December 10, 2020, Saudi Arabia's Ministry of Health reported new MERS-CoV cases, including two in people who had contact with camels.
Countries in or near the Arabian Peninsula that have reported MERS cases including Bahrain, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, United Arab Emirates, and Yemen.
On July 17, 2020, Public Health England cautioned health professionals to remain vigilant for MERS-CoV's clinical presentations. However, the probability that a cluster of severe acute respiratory infection cases in the UK, with unexplained etiology and requiring intensive care admission, is due to MERS-CoV remains very low but warrants investigation and testing. A history of travel to the Middle East would increase MERS-CoV's likelihood.
MERS-CoV Risk Assessment
The WHO said that on December 31, 2020, WHO encourages all Member States to continue their surveillance for acute respiratory infections and carefully review any unusual patterns based on the current situation and available information. The WHO does not advise special screening at entry points concerning this event, nor does it currently recommend applying any travel or trade restrictions.
The ECDC assessment of the risk of sustained human-to-human transmission poses a low risk to the EU, as stated in an ECDC rapid risk assessment.
The MERS novel coronavirus (MERS-CoV) causes more severe disease in people with underlying chronic medical conditions such as diabetes mellitus, renal failure, chronic lung disease, and compromised immune systems, says the WHO.
Humans are infected with MERS-CoV from direct or indirect contact with dromedaries. MERS-CoV has demonstrated the ability to transmit between humans. So far, the observed non-sustained human-to-human transmission has occurred mainly in healthcare settings, says the WHO.
MERS-CoV's demographic and epidemiological characteristics reported cases compared with the same corresponding periods in 2014–2020 do not show any signiﬁcant difference or change. The male age group, 50–59 years, continues to be at the highest risk for acquiring MERS-CoV infection as primary cases, says the WHO.
Only 2 patients in the USA have ever tested positive for MERS-CoV infection—both in May 2014—while more than 1,300 people have tested negative.
Humans are infected with MERS-CoV from direct or indirect contact with dromedaries. People should avoid drinking raw camel milk or camel urine or eating meat that has not been properly cooked.
And MERS-CoV has demonstrated the ability to transmit between humans.
A study published by The Lancet on October 6, 2020, presented data that indicate that human MERS-CoV infection is an occupational hazard in dromedary abattoir workers in Nigeria. They focus our attention on the potential for MERS-CoV transmission and human infection and the consequent threat to people living in Africa and to public health services.'
'Zoonotic infection of dromedary-exposed individuals is taking place in Nigeria and suggests that the extent of MERS-CoV infections in Africa is underestimated. Therefore, MERS-CoV could adapt to human transmission in Africa rather than the Arabian Peninsula, where attention is currently focused.'
'Therefore, African and Middle Eastern countries must invest more in surveillance and urgent priority research to fill major knowledge gaps in the epidemiology, transmission, pathogenesis, and evolution of MERS-CoV and SARS-CoV-2, especially because they are co-circulating.'
Most people infected with MERS-CoV developed severe respiratory illness, including fever, cough, shortness of breath, and fatal, says the CDC.
The median time from illness onset to hospitalization is approximately 4 days. In critically ill patients, the median time from onset to intensive care unit admission was approximately 5 days. Moreover, the median time from onset to death is approximately 12 days, says the CDC.
A study published in the CDC's June 2020 report conducted a systematic review of the evidence for treatment with pharmacologic and supportive therapies. They retrieved 3,660 unique citations; 20 observational studies met eligibility and studied 13 therapies.
Most studies were at serious or critical RoB; no studies were at low RoB. At moderate RoB, one study showed reduced mortality rates in severe MERS patients with extracorporeal membrane oxygenation; no other studies showed a significant lifesaving benefit to any treatment.
A MERS therapy study published on January 10, 2020, found that remdesivir and interferon had superior antiviral activity compared to lopinavir and ritonavir. In transgenic mice, both prophylactic and therapeutic doses of remdesivir improved lung function and reduced lung viral loads and severe pathology.
The team said the findings were similar to their earlier studies on remdesivir and severe acute respiratory syndrome coronavirus (SARS) and showed evidence of the potential to treat MERS-CoV.
MERS-CoV Diagnostic Tests
A May 2020 study developed and validated 2 species-independent protein-based assays to detect Middle East respiratory syndrome coronavirus functional antibodies that can block virus receptor-binding or sialic acid-attachment. Antibody levels measured in both assays correlated strongly with virus-neutralizing antibody titers, proving their use for MERS' serologic confirmatory diagnosis.
MERS-CoV testing version 2.1 was last updated by the CDC on August 2, 2019, which says, before collecting and handling specimens for MERS-CoV, determine whether the person meets the current definition for a “patient under investigation."
To increase the likelihood of detecting infection, the CDC recommends collecting multiple specimens from different sites at different times after symptom onset, if possible. The laboratory must follow the CDC rRT-PCR assay protocol in the USA.
U.S. CDC's MERS Frequently Asked Questions and Answers.
WHO MERS-CoV FAQs.
NOTE: This page's content is sourced from the CDC, WHO, clinicaltrials.gov, and the Precision Vax network of websites. This information was last fact-checked by healthcare providers, such as Dr. Robert Carlson.