WHO | Measles – Mexico

A measles epidemic is occurring in Mexico. Between January 1 and April 2, 2020 1,364 probable¹measles cases were reported, of which 124 were laboratory confirmed, 991 were rejected and 328 were under investigation. The age of confirmed measles cases ranged from three months to 68 years (median = 20 years), with 59% being men. An analysis conducted by the National Reference Laboratory (InDRE) identified the D8 genotype (similar to other countries in the region), the MVs for arming / GirSomnath.IND / 42.16 / for 17 confirmed cases.

Of the 124 confirmed cases, 105 were in Mexico City, 18 in Mexico and one in Campeche; the following is a summary of the epidemiological situation in each of them:

In Mexico City, 427 probable cases have been reported, 105 of which have been laboratory-confirmed and 83 are under investigation. Cases were confirmed in 14 City Hall, including Gustavo A. Madero (53 cases), Miguel Hidalgo (14 cases), Iztapalapa (9 cases), Cuajimalpa de Morelos (8 cases), Alvaro Obregon (7 cases), Xochimilco (4 cases) cases), Cuauhtémoc (2 cases), Tlahuac (2 cases), Tlalpan (2 cases), Coyoacán (1 case), Azcapotzalco (1 case), Milpa Alta (1 case) and Venustiano Carranza (1 case). All 105 confirmed cases in Mexico City were Mexican nationals and 60% were men. The highest proportion of confirmed cases were between the ages of 20 and 29 years (28%), followed by 2 to 9-year-olds (17%), 30 -39-year-olds (14%), one-year-olds (11%), infants younger 12 months (11%), 10 to 19 years (10%) and 40 years or more (9%). Of the confirmed cases, only 15 (14%) proved it² Vaccination history Vaccinations can be linked to missed vaccination opportunities, lack of access to vaccination services, scheduling restrictions that affect parents’ ability to take their children for vaccination, or lack of vaccine supplies. The most recent confirmed rash case appeared on April 2, 2020 and was reported at Gustavo A. Madero City Hall.

In Mexico, 162 probable cases have been reported, 18 of which have been laboratory-confirmed and 65 are under investigation. Confirmed cases were confirmed in eight municipalities of the State of Mexico, including Tlalnepantla (5 cases), Ecatepec de Morelos (4 cases), Nezahualcóyotl (2 cases), Tecámac (2 cases), Toluca (2 cases), Atizapán de Zaragoza (1 case) , Chimalhuacán (1 case), Naucalpan (1 case). In these 18 confirmed cases, all were Mexican nationals and 56% were male. The highest proportion of confirmed cases was reported between 20 and 29-year-olds (22%), followed by 1-year-olds (17%), 2-9-year-olds (17%), 30-39-year-olds (17%). , infants younger than 12 months (11%), 10 to 19 years (11%), and 40 or older (5%). Of the confirmed cases, three (33%) had a proven vaccination history. The latest confirmed case in the state of Mexico had a rash on March 27 and lives in the municipality of Tlalnepantla de Baz.

In Campeche, eight probable cases have been reported, one of which has been confirmed and seven are under investigation. The confirmed case is a five-year resident of Champoton County who had a rash on March 21, 2020. The case has a proven vaccination history with no travel history outside the state. The likely site of exposure was the city of Mérida, Yucatán.

The dates of the rash occurrence in confirmed cases in Mexico were between February 12 and April 2, 2020. Figure 1 shows the epidemic’s progress. An exponential increase in confirmed cases could be observed in the coming weeks.

Figure 1. Reported cases of measles by date of rash in Mexico. Between February 12 and April 2, 2020.

Source: Data published by the Mexican Health Secretary and reproduced by PAHO / WHO.

The WHO WHO region was declared measles-free in September 2016. However, Venezuela and Brazil lost their status of “measles” on July 1, 2018 and February 19, 2019, due to large epidemics of measles between 2018 and 2019. Out of 35 members of the State. 33 maintained their “no measles” status. In 2019, 14 countries in the Americas region reported confirmed measles cases, including Brazil (19,326 cases including 15 deaths), the United States (1,282 cases), the Bolivarian Republic of Venezuela (548 cases, including three deaths), Colombia ( 242 cases, including 1 death), Canada (113 cases), Argentina (107 cases), Mexico (20 cases), Chile (11 cases), Costa Rica (10 cases), Uruguay (9 cases), Bahamas (3 cases). Peru (2 cases), Cuba (1 case) and Saint Lucia (1 case). Between January 1 and April 4, 2020, seven countries reported confirmed measles cases, including Brazil (2,194 cases, 4 deaths), Mexico (124 cases), Argentina (54 cases, 1 death), United States (12 cases) , Uruguay (2 cases), Chile (2 cases) and Canada (1 case).

Public health response

Measures taken by health authorities include:

• Intensified epidemiological surveillance through active and retrospective institutional case finding, contact seeking and contact monitoring;
• Field vaccination activities;
• Risk communication through epidemiological notification;
• Training activities for field staff;
• Strengthening the laboratory network.

WHO risk assessment

Measles are highly contagious viral diseases that affect sensitive people of all ages and remain one of the leading causes of death among young children worldwide, despite the availability of safe and effective measles vaccines. The mode of transmission is contaminated by air or drops from the nose, mouth or throat. Initial symptoms that usually occur 10 to 12 days after infection include fever, usually accompanied by one of the following: runny nose, bloody eyes, cough, and tiny white spots on the inside of the mouth. A few days later a rash develops, which usually begins on the face and upper neck and gradually spreads downwards. The patient is infected four days before the onset of the rash, up to four days after the onset of the rash. There is no specific antiviral treatment for measles and most people recover within 2-3 weeks.

Among malnourished children and people with greater sensitivity, measles can also cause serious complications, including blindness, encephalitis, severe diarrhea, ear infection and pneumonia. Measles can be prevented by immunization. In countries with low vaccination coverage, outbreaks usually occur every two to three years and usually last between two and three months, although their duration varies depending on population size, crowds and population status.

Due to ongoing transmission, vaccination strategies and other actions are being implemented to control the epidemic by local and state governments in Mexico. There is a high risk of spreading the virus due to its high population density, such as Mexico City, in which high vaccination coverage could allow slow but steady transmission. At regional level, the potential impact is considered moderate given the implementation of routine immunization programs, prevention and control capacities in other countries of the region, and travel restrictions in many countries and regions of the region due to the COVID-19 pandemic.

Due to the current COVID-19 pandemic, there may be a risk of interruption of routine immunization activities due to the workload of the COVID-19-related health system and the reduced need for vaccination due to the physical needs of distance or community reluctance. Discontinuation of immunization, even briefly, can result in an increased number of susceptible persons and increase the likelihood of epidemic vaccines (VPD), such as measles.

Tip of WHO

From September 1, 2017, the Pan-American Health Organization WHO Regional Office of the Americas (PAHO / WHO) shares information on these outbreaks with its Member States and warns of the risk of an epidemic of measles import cases as well as the possibility of reintroduction of the disease in low-coverage areas vaccination. In light of the continuing reports on import cases of measles from other regions and the continuing epidemic of America, PAHO / WHO calls on all Member States to follow the new recommendations on Immunization guidelines in the context of COVID-19 settings.

Among the recommendations for measles countries are the following:

Vaccination

• Involve the National Immunization Technical Advisory Group (NITAG) in deciding on the continuity of vaccination services.
• In healthcare settings where vaccinations are conducted, it is critical that healthcare professionals look for signs and symptoms of respiratory illnesses and offer a surgical mask to patients with flu-like symptoms and refer them for medical evaluation, in accordance with local protocols for the initial triage of patients with suspected Covide-19th
• Although there are currently no known medical contraindications for the vaccination of a person who has had contact with the COVID-19 case, it is recommended to delay vaccination until the quarantine is completed (14 days after the last exposure).
• In circumstances of a vaccine-preventable disease (VPD) outbreak, the decision to conduct mass vaccination campaigns in response to an epidemic will require an assessment of the risks and benefits of the individual cases and must take into account the health system’s ability to effectively carry out a safe and high-quality mass campaign in in the context of the COVID-19 pandemic. The assessment should assess the risks of delayed response in relation to the risks associated with immediate response, both in terms of morbidity and mortality for VPD, and the potential impact of further transmission of SARS-CoV-2 virus.
• If a VDP outbreak occurs, the risk and benefits of conducting a response vaccination campaign should be evaluated, taking into account the health system’s ability to effectively carry out a safe and quality mass campaign in the context of the COVID-19 pandemic. The assessment should assess the risks of a delayed response in relation to the risks associated with the immediate response, both in terms of morbidity and mortality for VPD, and the potential impact of further transmission of SARS-CoV-2 virus. If a response vaccination campaign is to be implemented, rigorous measures are needed to support standard and prevention and control of COVID-19 infections, adequate treatment of injection waste, protection of healthcare professionals and protection of the public. If response vaccination campaigns are delayed, periodic assessment based on local morbidity and mortality of the VPD is needed to assess the risk of further delay.
• Immunization services should be resumed when the risk of SARS-CoV-2 transmission is reduced and the capacity of the health system is restored sufficiently to continue these activities. It is likely that some level of SARS-CoV-2 transmission will continue to be ongoing when services are retried. Strict infection prevention and control measures and social distancing practices are likely to continue in the early stages of continuing the vaccination service. NITAG should advise the country on how to continue the service and which population should be prioritized.
• Vaccine at-risk populations in areas in which measles virus is circulating without evidence of vaccination or immunity against measles and rubella, such as healthcare staff, people working in basic services, captive populations and transportation (hospitals, air ports, prisons, hostels, border crossings, urban mass transit and more) as well as international travelers.
• Vaccine at-risk populations (no evidence of vaccination or immunity against measles and rubella), such as healthcare professionals, persons working in tourism and transportation (hotels, airports, border crossings, mass urban transport, etc.) and international travelers.
• Maintain supplies of measles vaccine (MR) and / or MMR vaccines and syringes / supplies to prevent and control imported cases.

Epidemiological surveillance

• Surveillance systems must continue to implement early detection and management of VPD cases, at a minimum, for diseases with global surveillance mandates and removal targets such as measles and rubella, among others.
• During an epidemic and when it is not possible to confirm suspected cases in a laboratory, the confirmed case classifications may be based on clinical criteria (fever, rash, cough, crust, and conjunctivitis) and epidemiological link, so that response is not delayed.
• The routine monitoring of other VPDs should continue for as long as possible; where laboratory testing is not possible, samples should be stored appropriately for confirmation when laboratory capacity permits testing. Countries should ensure sufficient sample storage capacity at the provincial and central levels, and this should be monitored regularly.
• Enhance epidemiological surveillance in border areas to quickly detect and respond to highly suspected measles cases.

Quick response

• Enable rapid response to imported measles cases to avoid reestablishing endemic transmission, by activating rapid response teams trained for this purpose and applying national rapid response protocols when there are import cases. Once the Rapid Response Team is activated, constant coordination between the national and local levels must be ensured, with stable and fluid communication channels between all levels (national, sub-national and local).
• Establish appropriate hospital case management during the outbreak to avoid nosocomial transmission, with appropriate referral of patients to isolation rooms (for any level of care) and avoid contact with other patients in waiting rooms and / or other hospital rooms.

¹Measles / rubella case definition in Mexico: Any person of any age with fever and maculopapular rash, and one or more of the following signs and symptoms: cough, measles, conjunctivitis or adenomegaly (retroauricular, occipital or cervical). available here.

²Confirmed in the immunization record card.

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