measles outbreak new zealand 2019 in an international context of the 20… · 2012: global measles...

Measles outbreak New Zealand 2019 in an international context

Dr. Gerard Sonder PhDPublic health physician (in the Netherlands)

Epidemiologist, biologist

Outline

1. Introduction Measles 2. Measles vaccination and epidemiology worldwide3. Measles vaccination and epidemiology New Zealand 4. The measles 2019 outbreak New Zealand5. Conclusions

Outline

1. Introduction Measles 2. Measles vaccination and epidemiology worldwide3. Measles vaccination and epidemiology New Zealand 4. The measles 2019 outbreak New Zealand5. Conclusions

1. Introduction measles

• Incubation period (exposure to rash) 7-18 days • Contagious: 4 days before to 4 days after onset of rash• Symptoms

• 7-14 days after infection: high fever, cough, runny nose (coryza), and red, watery eyes (conjunctivitis).

• 2-3 days after start symptoms: Koplik’s spots• 3-5 days after start symptoms: rash

1. Introduction measles

• Complications:• Otitis media (5-10%)• Laryngotracheobronchitis (5—10%)• Bronchiolitis (5-10%)• Pneumonia (1-5%) by measles virus or bacterial superinfection• Encephalitis (0.1%)

• Measles encephalitis • SSPE (subacute sclerosing panencephalitis): progressive, starts 4-10 years after infection,Incidence 4-11/100,000 measles patients, higher in young baby’s)

1. Introduction measles

• Measles is the most contagious disease• R0 (Basic Reproductive Rate) ≈ 12-18 • CFR 0.1% in developed and 10-15% in developing world • CFR related to malnutrition and quality healthcare haemorrhagic

exanthema, skin infections, diarrhoea, keratitis and blindness

• Surviving measles lifelong immunity

1. Introduction measles: outbreaks

https://vk.ovg.ox.ac.uk/vk/measles

R0 (Basic Reproductive Rate) ≈ 12-18

1. Introduction measles: outbreaks

Source: Public Health England

1. Introduction measles: Herd immunity

For measles: R0 = 12-18

Herd immunity threshold = 1 - 1/R0

Herd immunity threshold measles: 92-94%

(Vaccination coverage needed: > 95%)

1. Introduction measles: history

854 First description of measles-like symptoms Iran

1492 Europeans introduced measles (and many other IDs) Americas. Indigenouspopulation reduced 50-90%

Americas

1657 First reported measles outbreak in colonial America United States

1850-1859 Measles kills one fifth of Hawaii's population within a decade. Hawaii (US)

1870-1879 Epidemic Fiji kills 20% of the population Fiji

1911 First introduction on Rotuma island, kills 491/2,600 (19%) Polynesia

1916 Discovery immunoglobuline in France France

1951 Danish traveller introduced virus Inuit population (n=4,262) Greenland: attack rate 99.9%. Use of immunoglobuline reduces CFR: 1.8%

Greenland

1963 First vaccine (Edmonston-B strain) developed and licensed United States

https://en.wikipedia.org/wiki/Timeline_of_measles

Outline

1. Introduction Measles 2. Measles vaccination and epidemiology worldwide3. Measles vaccination and epidemiology New Zealand 4. The measles 2019 outbreak New Zealand5. Conclusions

2. Vaccination and epidemiology worldwide

• Before 1963 major epidemics 2–3 years with 2.6 million deaths each year

https://www.who.int/news-room/factsheets/detail/measles

2. Vaccination and epidemiology worldwide

MMWR: Nov 30, 2018 / Vol. 67 / No. 47

In 2018, 86% children received one measles vaccine by their first birthday – up from 72% in 2000.

In 2018, more than 140 000 people died from measles – mostly children under the age of 5 years

2. Vaccination and epidemiology worldwide

https://measlesrubellainitiative.org/resources/advocacy-tools/infographic/

2. Vaccination and epidemiology worldwide

MMWR: Nov 30, 2018 / Vol. 67 / No. 47

2. Vaccination and epidemiology worldwide

*global partnership led by the American Red Cross, United Nations Foundation, Centers for Disease Control and Prevention (CDC), UNICEF and WHO

2001: Measles and Rubella initiative* :

• Ensure no child dies from measles or is born with congenital Rubellasyndrome

• Helps countries to plan, fund and measure efforts to stop measles and rubella for good.

2. Vaccination and epidemiology worldwide

2015 goals (not achieved):• Reduce measles death by 95%

compared to 2000• Achieve regional elimination goals

2020 goals:• Achieve 2020 global elimination

goals (5/6 WHO regions)

2012: Global Measles and Rubella Strategic Plan 2012-2020

Elimination status and WHO regions

African Region (AFRO)Region of the Americas (PAHO)South-East Asia Region (SEARO)European Region (EURO)Eastern Mediterranean Region (EMRO) Western Pacific Region (WPRO)

Elimination: “the absence of endemic measles virus transmission in a defined geographical area (e.g. region or country) for at least 12 months in the presence of a surveillance system that has been verified to be performing well.”

Elimination status and WHO regions: 2016

Source: https://www.paho.org/hq/index.php?option=com_content&view=article&id=12526:measles-elimination-in-the-americas&Itemid=40721&lang=en

Anti-vaxxers

2012

1998

Instable countries in theworld: Syrian war 2011

Incident Samoa 2019

Samoa: as of 22 January 2020:

-5,707 cases reported-83 deaths (children < 5 years old)-Mortality rate 25 per 10,000 in < 5 year olds

Craig et al. Lancet March 2020

Measles cases worldwide

2016: instability Venezuela

October 4, 2019

Outline

1. Introduction Measles 2. Measles vaccination and epidemiology worldwide3. Measles vaccination and epidemiology New Zealand 4. The measles 2019 outbreak New Zealand5. Conclusions

3. Measles vaccination New Zealand

1969 introduction for 10 months-5 year old children

1974 immunisation at 12 months old recommended

1978 5 year measles elimination plan implemented

1990 single dose MMR introduced

1992 second dose MMR introduced for 11 year olds (in response to 1991 outbreak)

1996 MMR1 shifted from 12 months to 15 months to increase uptake (combined with other vaccines) implemented during 1997 outbreak

Coverage unknown but always too low to prevent outbreaks

Coverage in 1990s estimated at 80% for MMR1 Aging population ->> Immunity gap

No registration ->> not identifyable

Hayman et al. Vaccine. 2017

3. Measles vaccination New Zealand

• 2005: introduction National Immunisation Register (NIR). • Coverage went up to 87%-93% for MMR1• Coverage MMR2 83%-88% Coverage never reached 95%

Equity gaps persisted: EthnicitySocio-economic statusRegion

Turner N. A measles epidemic in New Zealand: Why did this occur and how can we prevent it occurring again? N Z Med J. 2019 Oct 25;132(1504):8-12

3. Measles vaccination New Zealand

Immunity gap confirmed by serosurvey (n=5,027)

3. Measles vaccination New Zealand

4. Measles epidemiology New Zealand

Measles notifications (confirmed and probable cases) in NZ from 1997 to 2014.

Analysis of all 1137 cases 2007-2014:-Majority very young unvaccinated, but increasing number in teenagers and young

adults-Absolute numbers highest in European NZers, wealthier 5-17 year-Incidence highest in youngest most disadvantaged Pacific populations Hayman et al. Epid Inf 2017

4. Elimination plan NZ

2020 goals:Achieve 2020 global elimination goals (5/6 WHO regions)

Western Pacific Region (WPRO)

4. Epidemiology New Zealand

• In 2016, Ministry of Health established the New Zealand National Verification Committee (NVC)

• Reports elimination progression annually to the WHO Regional Verification Committee (RVC) WPRO

• The RVC officially granted New Zealand ‘measles and rubella elimination status’ in 2017 but cautioned that ‘significant immunity gaps remained in New Zealand among demographic and geographic risk groups, in particular older adolescents and young adults, and the Māori population’

Outline

1. Introduction Measles 2. Measles vaccination and epidemiology worldwide3. Measles vaccination and epidemiology New Zealand4. The measles 2019 outbreak New Zealand5. Conclusions

4 Elimination status, but increasing risks

NZ less and less isolated from the world

Travel Worldwide risk increased -vaccination coverage declines.-surge (300%) in measles cases with 140,000 death in 2018.

New Zealand vaccination status- Historically sub-optimally vaccinated population (immunity gap)-Declining coverage new birth cohorts

5. Preparedness and response to 2019 measles outbreak• Measles notifiable disease • Every case diagnosed has to be reported to Public Health Unit (PHU)• PHU reports cases to ESR for national surveillance • PHU starts source and contact tracing, isolation cases, vaccinates,

administers immune globulins, quarantines contacts following the Communicable Disease Control Manual.

5. Response to New Zealand 2019 measlesoutbreak• Health Emergency plans• Containment on local scale• Upscaling procedures if needed

4.Measles outbreak NZ 2019

5. Response to outbreak: Canterbury

• First case 12 February 2019• Last case 16 May 2019• Total 39 cases• Total 22,000 MMR vaccines given

5. Response to the outbreak: Auckland

• First case 27 February• Contact tracing, immunisation isolation and quarantine• Vaccination wider groups around cases; schools• Targeting risk groups, by ethnicity and age• Introduction MMR0 to protect younger children• Increasing media attention• 30 August: establishment of National HealthCoordination Centre NHCC

5. Response to the outbreak

• First case 27 February• Last case early 2020• Total almost 2,185 cases• In NZ > 104,000 MMR additional vaccines administered• Genomic sequencing revealed: +18 separate introductions

maintain elimination status

• No death (!)

Measles outbreak 2019

Canterbury

Auckland

Waitemata

Counties

Counties

Auckland Waitemata

Northland

Source: ESR

Measles outbreak 2019total 2185 cases

Age Number (%) Hospitalised (35%)

< 12 months 275 (13) 176 (64)

12 mnths-2yrs 245 (11) 127 (52)

3-4 year 57 (3) 19 (33)

5-9 year 85 (4) 10 (12)

10-19 year 455 (21) 116 (26)

20-29 year 711 (33) 214 (30)

30-49 year 325 (15) 88 (27)

50+ 32 (1) 18 (56)Ethnicity Number (%)

Maori 523 (24)

Pacific 893 (41)

Asian 158 (7)

EUR NZ 563 (26)

MELAA 31 (1)

85% of cases in Northern region

Catch-up campaign 2020 NZ

• 300,000 young adults aged between 15 and 30 are not immune to measles

• $40 million to deliver the 350,000 vaccines now in the country.

-often not known who is already immune

-closing the ‘registration gap’ of majorimportance

Outline

1. Introduction Measles 2. Measles vaccination and epidemiology worldwide3. Measles vaccination and epidemiology New Zealand4. The measles 2019 outbreak New Zealand5. Response to the 2019 outbreak 6. Conclusions

6. Conclusions

• Measles outbreaks, as most infectious disease, are hard to control; isolation and reactive vaccination usually too late

• In a changing world, declining vaccination coverage and resurgence of measles is a problem

• Vaccine hesitancy is important cause • Measles is the first disease to cause outbreaks when vaccination coverages decline• Until COVID, because of ever increasing travel, NZ became less and less isolated:

Frequent introductions of measles viruses unavoidable• Only way to prevent future outbreaks is by improving the vaccination coverage in NZ:

• Closing the immunity gap (current vaccination campaign) including registration• Improving coverage in new birth cohorts: needs continuous attention:

• Deprived ethnic groups• Vaccine hesitancy groups