Malawi vaccination drive: An integrated immunization campaign against typhoid, measles, rubella, and polio; health benefits and potential challenges

ABSTRACT

Vaccination stands as one of the most important scientific discoveries and public health achievements in the fight against diseases. For over a century, millions of early childhood deaths have been averted through routine immunizations. However, to prevent the morbidity and mortality associated with vaccine-preventable diseases and their complications and optimize the control of vaccine-preventable diseases in communities, high uptake rates must be achieved. Mass immunization campaigns (MICs) have globally been used to introduce new vaccines for major infectious diseases and improve coverage of routine vaccines through catch-up campaigns. Malawi recently undertook such a campaign to introduce a highly efficacious typhoid conjugate vaccine and provides a catch-up to measles, rubella, and polio. Such campaigns are associated with multiple benefits. However, the MICs are associated with multiple challenges to be successfully administered. In this review, we highlight recent MIC, vaccine coverage, and potential challenges and benefits and offer recommendation for future preventive campaigns.

Introduction

The evidence demonstrating the benefits of immunization is overwhelming. Immunization has been proven as one of the most successful interventions in improving health outcomes. It is one of the greatest public health achievements of the twentieth century.¹ Indeed, vaccines have been proven to be the most reliable warlords in the fight against existing and emerging infectious diseases. However, to prevent the morbidity and mortality associated with vaccine-preventable diseases and their complications and optimize the control of vaccine-preventable diseases in communities, high uptake rates must be achieved.² High vaccine uptake rate is a requirement to achieve herd immunity; however, vaccine uptake is influenced by a number of factors.² In addition to vaccine hesitancy, factors such as accessibility also determine vaccine uptake rates. Door-to-door campaigns have largely been utilized in promoting vaccine uptake and expanding coverage rate, especially in hard-to-reach areas.^3,4 It has also been used in promoting new vaccine enrollment before actual integration into routine vaccination programs.⁴

Even though the use of a mass immunization campaign (MIC) has been and still remains controversial, its benefits in averting major infectious diseases cannot be undermined. Well-conducted campaigns have increased vaccine coverage levels and decreased disease morbidity and mortality. The World Health Organization’s (WHO) global initiative has eradicated smallpox and reduced the incidence of measles and polio deaths through MICs.⁵ MICs can increase awareness of vaccination and may be appropriate in situations where new programs are to be initiated and in disease eradication efforts when specific time goals are set.

In Malawi, MICs have been used several times to curb resurging outbreaks and emerging infectious diseases. Such a similar campaign was conducted in March 2022 following the resurgence of polio cases.⁶ The campaign targeted more than 2.9 million under-five children. In the quest to fight the major infectious diseases, the government of Malawi (GoM), in collaboration with its partners, has embarked on another campaign against typhoid, measles, rubella, and polio.⁷ This recent MIC comes at a time when the country is recovering from the devastating effects of Tropical Cyclone Freddy. It is in this regard that in this review, we highlight more about mass immunization, health benefits, and potential challenges and offer recommendation for future campaigns.

Disease burden

The recent immunization campaign targets major infectious diseases that cause significant morbidity and mortality, especially in under-five children. In 2019, over 9 million typhoid fever cases occurred globally, causing over 110,000 deaths.⁷ Typhoid is usually spread through contaminated food or water and is usually difficult to treat due to the emergence of drug-resistant strains.^8,9 In Malawi, typhoid is endemic, with more than 16,000 estimated cases per year.¹⁰ Most of the times, the disease affects children under 15, causes prolonged illness, causes significant economic burden on the family, and is associated with numerous long-term complications.^8–10

While polio was grossly eliminated in Malawi for 30 y, the year 2022 was a major setback to the country following the detection of wild poliovirus type 1 (WPV1) in an acute flaccid paralysis case in Lilongwe.⁶ The isolated WPV1 virus was highly divergent from the closest genetic relative and is virologically linked to circulation in Pakistan in 2019. This recent polio comeback to the world has been attributed to relaxation in vaccination, especially in the aftermaths of the COVID-19 pandemic.

Measles is one of the leading causes of death among young children, even though a safe and cost-effective vaccine is available.¹¹ Since 2018, the world has experienced a resurgence of measles cases. All WHO regions experienced at least one or more large-scale measles outbreaks, necessitating response efforts by affected national governments and partners to contain and end the outbreaks.¹¹ While much progress has been made, including more than 56 million measles-related deaths prevented through vaccination from 2000 to 2021, measles still claimed the lives of almost 130,000 people (mostly children) in 2021.¹² In 2021, the estimated number of measles cases was 9.5 million.¹² The health consequences of measles and rubella infection can be lifelong, including economic losses for individuals, families, and societies. Malawi experienced its worst measles epidemic in 2010. More than 130,000 cases of measles were reported during the outbreak. Since then, the number of cases has greatly declined up to 5 in 2021.¹³

Vaccination coverage in Malawi: gains and challenges

Since its launch in 1979, child immunization has remained a key preventive health priority area for GoM. Since then, various vaccines have been introduced into the extended program of immunization. During the launch of the Expanded program of Immunisation (EPI) in 1979, vaccines against six diseases were introduced: a dose of Bacillus Calmette–Guerin; three doses of diphtheria, tetanus, and pertussis; at least three doses of oral polio vaccine; and one dose of measles-containing vaccine.¹⁴ Numerous other vaccines have also been introduced and administered in the country including the pneumococcal conjugate vaccine, monovalent rotavirus vaccine, malaria vaccine, oral cholera vaccine, and now the conjugate typhoid vaccine.¹⁴ For many years, Malawi has sustained a high coverage of immunization, with well above 80% of the population having received the six basic vaccinations. This has led to a reduced burden of infectious diseases, especially in under-five children.¹⁵ In addition to the routine immunization, supplemental immunization activities, popularly known as mass vaccination campaigns, have contributed to high immunizations rate of Malawian children, especially against measles. Since 1996, periodic immunization campaigns targeting polio and measles have been successfully conducted in accordance with the WHO recommendation. These campaigns relished a massive gain in an average vaccination coverage of 95%.^14,15 Despite Malawi sustaining a high vaccination coverage, shockingly, recent reports have indicated a decline in vaccination coverage for all the six basic vaccinations. Malawi reported a sharp decline in the number of fully immunized children from 81% in 2010 to 76% in 2016.¹⁶ Various obstacles to reaching every child with the full complement of vaccines have been identified in some settings. Studies from Malawi have reported that women’s low education, having one or no antenatal visits, having no immunization card, having an immunization card but not seen, residing in poor households, having a large number of children, and living in the central region were the most significant factors associated with decreased odds of achieving vaccination coverage and complete vaccination.^17,18 However, the factors affecting vaccination coverage are beyond that. They are multifactorial and complex. The vaccination coverage gains in Malawi were also greatly affected by the COVID-19 pandemic. Misinformation and conspiracy theories and beliefs among the general society largely affected vaccination coverage in Malawi.¹⁹ Most of the parents were afraid that their children would be given COVID-19 vaccine without their consent during a routine in immunization program. It is against this background that, as of the year 2019, the Malawi Expanded Programme on Immunization reported that 75% of children aged 12–23 months had received all eight basic vaccinations.^19,20 Furthermore, there was a more pronounced decline in vaccination in 2021, which corresponded with peaks in COVID-19 infections that had higher cumulative cases and case fatality rates.²⁰

Mass immunization campaign: what are the health benefits and potential challenges?

The MIC, an integrated “catch-up” campaign providing vaccines against typhoid fever, measles, rubella, and polio, as well as a vitamin A supplement, is very timely. The ambitious 1-week campaign targeting more than 9 million children, if successful, will lead to massive gains in preventing major infectious diseases and averting morbidity in Malawi. The immunization campaign is targeting key health risks in children, namely polio, measles, and typhoid fever. The campaign is coming at a time when the world is experiencing a resurgence of polio and measles cases in the aftermaths of the COVID-19 pandemic following a slowed immunization drive.²¹ The campaign is also happening at a time when Malawi is currently grappling with the deadliest cholera outbreak in a decade and recovering from the devastating impact of the tropical storm – Cyclone Freddy. The Tropical Cyclone Freddy led to death, displacement, destruction, and reduced or severed access by communities to essential services, including health care and education.²² This led to a displacement of 659,278 people in 747 camps, including 336,252 women and 323,026 men. Health services were significantly affected by Freddy, with at least 83 health facilities damaged or destroyed.²² This may have likely impacted routine immunization among the affected communities. Also, the disruption of water, sanitation, and hygiene facilities may likely lead to an increase in the occurrence of waterborne diseases including typhoid.

The introduction of typhoid conjugate vaccine (TCV) in the campaign will also lead to significant gains in the fight against typhoid. There has been a recent rise in cases of drug-resistant typhoid.^9,10 This has led to prolonged infection, higher morbidity, and increased economic costs in the management of the disease. A new TCV is safe, effective, and WHO-recommended for routine immunization as a part of a cost-effective, integrated approach to typhoid prevention and control alongside safe water, sanitation, and hygiene interventions.²³ The introduction of the vaccine during a catch-up campaign provides a better opportunity for increased coverage, even in hard-to-reach areas. The typhoid vaccine is highly efficacious in all age groups (including <2 y), with immunity lasting up to 4 y following a single-dose vaccination.²³ The typhoid conjugate offers a better relief for the country as it is currently experiencing a high prevalence of multidrug-resistant typhoid fever.

While no vaccine is 100% effective, when used broadly in communities, several vaccine-preventable diseases could be eliminated and some may be eradicated. The MIC offers an opportunity for increased access and coverage, especially in hard-to-reach areas. With increasing numbers of extreme weather events due to climate change, as well as urbanization, migration, and continued gaps in access to safe water and improved sanitation, the risk of other outbreaks is also increasing. This proactive vaccination that targets nearly half of the country's population is more likely to avert the occurrence of such anticipated outbreaks.

With an increased rate of drug-resistant pathogens, primary prevention offers a better opportunity for most developing countries including Malawi. The cost of purchasing second-line and third-line treatment drugs can simply be averted by proactive actions such as these.

While the whole idea of mass vaccination campaigns may look more exciting, a 100% vaccine coverage is not guaranteed. The aftermaths of the COVID-19 pandemic saw rising concerns of vaccine hesitancy among the general population.²⁴ Most parents and caregivers have declined immunization for their children. This hinders the current progress that has been made in the fight against infectious diseases. High vaccine uptake rates, specific to each vaccine-preventable disease, are needed to achieve and sustain community-level immunity in order that disease risk can be lowered beyond what would be predicted by vaccine coverage alone.

Majority of children may not be vaccinated due to the growing rate of vaccine hesitancy among the general population.²⁵ The rate of vaccine hesitancy in Malawi greatly increased following conspiracy theories that rose during the COVID-19 pandemic. This may likely influence the current immunization campaign.

Conclusion

Catch-up immunization campaigns provide a major complement to routine immunization programs. Although highly effective in improving vaccination accessibility and coverage, these MICs need to be well coordinated and planned. They also need intensive social promotion and community engagement before actual enrollment of the vaccine. In addition, these MICs need to be coupled with research to determine coverage and explore the factors determining hesitancy in low-uptake areas.

Funding Statement

The author(s) reported that there is no funding associated with the work featured in this article.

Disclosure statement

No potential conflict of interest was reported by the author(s).