Meningococcus (Neisseria meningitidis) is one of the leading bacterial causes of meningitis in both children and adults. This article is based on the book Prevention of meningococcal disease in Vietnam (Vietnam Association of Preventive Medicine) and Part III of the book Recommended vaccination schedules for all ages in Vietnam (Vietnam Association of Preventive Medicine, 3rd edition, 2026).

How dangerous it is

Without treatment, the case fatality rate can reach about 50%.
Even with timely antibiotic treatment, the fatality rate is still above 10%, highest in infants.
The disease can go from non-specific symptoms in the first 4–6 hours to severe illness and death within 24 hours.
About half of the infants who survive invasive disease have after-effects.

Source: Prevention of meningococcal disease in Vietnam (Vietnam Association of Preventive Medicine), Lesson 5, sections 1 and 2.1.1, pp. 141–142.

Forms of the disease

The incubation period is 1–10 days, usually less than 4 days. There are almost no symptoms during this time, or only a mild upper respiratory infection.

When the disease starts, there are two main clinical pictures:

Meningitis: about 50% of cases.
Sepsis: with meningitis in 35–40%, without meningitis in 10–15%.

Source: Prevention of meningococcal disease in Vietnam (Vietnam Association of Preventive Medicine), Lesson 5, section 2.1.1, p. 142.

Signs that mean going to hospital immediately

Sudden high fever, headache, vomiting.
Stiff neck, sensitivity to light. Infants may have a bulging fontanelle. Very young babies often do not show clear signs of meningitis, so the absence of these signs does not rule out the disease.
Drowsiness, confusion, seizures.
A purpuric rash on the skin: red-purple spots or patches with ragged edges that do not fade when pressed. The rash may become necrotic in the centre (purpura). Purpura is seen in about 50–60% of invasive cases. A rash that rapidly increases in number or size is a sign that the disease is becoming fulminant.

In children, signs of meningitis usually appear about 12–15 hours after the first symptom. So do not wait for all the symptoms before seeking care.

Source: Prevention of meningococcal disease in Vietnam (Vietnam Association of Preventive Medicine), Lesson 5, section 2.1.1, pp. 143, 150.

Who is at high risk

Children under 5, especially under 6 months.
Adolescents and young people aged 15–24 living in groups: dormitories, barracks.
Immunocompromised people, people without a spleen or with a poorly functioning spleen.
Close contacts of a person with the disease.
People travelling to areas with an outbreak.

Source: Prevention of meningococcal disease in Vietnam (Vietnam Association of Preventive Medicine), Lesson 5, section 2.1.1, p. 142; Lesson 8, p. 254.

Serogroups in Vietnam

There are 12 meningococcal serogroups. Serogroups A, B, C, W, X and Y cause most cases. In Vietnam, serogroup B dominates in the studies cited by the book:

A study in the military in 2021: 91% of 69 invasive cases were serogroup B, with 2 cases of serogroup W.
A study in the South from 1980 to 2019: 94% serogroup B, the rest serogroup C.
In healthy carriers: serogroup B 56%, serogroup C 21%.

The book notes that there is not yet enough data on the distribution of serogroups nationwide, and that this distribution can change over time. The Vietnam Association of Preventive Medicine therefore recommends broad protection against all of serogroups A, B, C, W and Y.

Source: Prevention of meningococcal disease in Vietnam (Vietnam Association of Preventive Medicine), Foreword, p. 3; Lesson 1, p. 30; Lesson 3, p. 125; Lesson 8, pp. 255–256.

How to prevent it

Vaccination. This is long-term prevention. Group B vaccine can be given as early as 2 months of age; A, C, W, Y vaccines are given in the first year of life. Adolescents and people at risk also need to be vaccinated. For the vaccines and schedules, see the article "Meningococcal vaccines available in Vietnam and schedules by age".
Take preventive antibiotics after close contact with a patient, ideally within 24 hours of the case being diagnosed.
Good hygiene: wash hands with soap, wear a mask when coughing, do not share eating utensils, keep the home well ventilated.
If you notice suspicious signs, see a doctor or tell the nearest health facility straight away.

Source: Prevention of meningococcal disease in Vietnam (Vietnam Association of Preventive Medicine), Lesson 6, sections 2.1–2.2, pp. 170–177.