During the Covid-19 pandemic, co-infections with other pathogens were observed in some patients and linked to worse outcomes.

Understanding what a co-infection is may help to improve treatment and prevention.

Co-infection happens when the body is infected by multiple pathogenic species (i.e. bacteria, viruses, fungi, etc) concurrently or consecutively.

For example, a child who has influenza also gets a pneumococcal infection at the same time.

Other terms used to identify co-infection include multiple infection, concurrent infection, simultaneous infection and polymicrobial.

Types of co-infection

There are three types of co-infection:

> Concurrent acute infection

This is when multiple infections occur at the same time.

One of the more common concurrent infections is the combination of influenza and pneumococcal pneumonia.

The body is more susceptible to a respiratory bacterial infection (pneumococcus) during a viral infection (influenza).

During the Covid-19 pandemic, there were reports of varied cases of SARS-CoV-2 viral co-infection with other respiratory pathogens.

The dengue virus and Mycoplasma pneumoniae bacteria can also attack the body concurrently.

Other combinations are also possible.

> Secondary/sequential infection

This is when a secondary infection occurs after the initial infection has subsided, due to a suppressed immune system.

A common example is otitis media – a ear infection usually caused by pneumococcus or Haemophilus influenzae, which often occurs after a respiratory syncytial virus (RSV), coronavirus or adenoviral infection.

This delayed secondary infection is also referred to as a super-infection.

> Concurrent with chronic infection

An underlying chronic infection can also lead to co-infection.

For example, in HIV (human immunodeficiency virus) infection, which impairs the immune system, the body becomes more susceptible to opportunistic pathogens such as Mycobacterium tuberculosis, which causes tuberculosis.

Indeed, HIV-tuberculosis co-infection has been a major contributor to the rise of global tuberculosis infections.

Worse complications

Compared with single infections, co-infections result in poorer health outcomes and tend to exacerbate infections.

An infection with influenza followed by pneumococcus could lead to a fatal outcome.

Animal studies have shown that the damage to the airways caused by influenza can allow fatal secondary infection with pneumococcus.

If they survive, patients of co-infection may suffer severe long-term effects such as blindness, chronic diarrhoea, chronic inflammation, carcinoma, immunosuppression, liver fibrosis, meningitis, renal failure and rheumatic fever.

Co-infection also complicates treatment when it involves different pathogens, e.g. bacteria and virus.

Antivirals or antibiotics are typically used to treat either viral or bacterial infections, but the effect of these medications on concurrent infections is still unclear.

Unknown underlying interactions may reduce treatment efficacy, or even aggravate the co-infection. It is crucial to understand these specific interactions to identify suitable treatment strategies.

In most cases, prevention through vaccination is the recommended option.

Many studies on influenza-pneumococcus co-infection have highlighted the potential of pneumococcal vaccination, in addition to an annual influenza vaccination, as a key strategy to reduce death and illness during an influenza outbreak.

One study also suggested pneumococcal and H. influenzae type b (Hib) vaccination as a viable supplementary strategy to reduce secondary co-infections in Covid-19 cases.

This was after the researchers found a strong correlation between higher rates of pneumococcal vaccination in nations and cities with lower Covid-19 illness and death.

Other co-infection cases may also benefit from vaccination against any of the pathogens involved.

However, more research is required to understand specific co-infections.

Even if pneumococcal vaccination does not provide direct protection against influenza or Covid-19 co-infections, it will reduce hospital visits and admissions, and decrease the burden on healthcare resources.

A final note

Being infected with one disease is unpleasant enough; a second infection due to the first one is so much worse.

Hence, it’s always wise to provide your child with greater protection against infections.

The inclusion of pneumococcal vaccination in the National Immunisation Programme (NIP) is a welcome step towards providing better healthcare for the nation.

A more comprehensive vaccination course would ensure that you, your family and those at risk are better protected against both infections and possible co-infections.

Datuk Dr Zulkifli Ismail is a consultant paediatrician and paediatric cardiologist. This article is courtesy of the Malaysian Paediatric Association’s Positive Parenting programme in collaboration with expert partners. For further information, please email starhealth@thestar.com.my. The information provided is for educational and communication purposes only, and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.