Recognition and management of COVID-19 and other influenza-like illnesses: a guide for paramedics

SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease 2019 (COVID-19) (Jutzeler et al, 2020).

The median incubation time is around 5.1 days, and 97.5% of those infected develop symptoms within 11.5 days (Lauer et al, 2020). However, it is possible that incubation periods may be longer in older adults, probably because of a dampened immune response (Kong, 2020).

The SARS-CoV-2 virus enters the patient's body cells through the S spike protein, which can cause inflammation in the infected individual's lung cells, myocytes and endothelial cells (Azer, 2020), This can lead to tachycardia, hypoxia, low and high systolic blood pressure, palpitations, low oxygen saturations, unilateral and bilateral crackles, sibilant wheeze and rhonchi (Jutzeler, 2020).

Common symptoms of COVID-19 include cough, fever, anosmia (lost/changed sense of smell), ageusia (lost/changed taste), sore throat, myalgia (muscle aches/pain), fatigue, headache, dyspnoea, diarrhoea and rhinorrhoea (runny nose). However, 25% of infected individuals are asymptomatic (Alene et al, 2021). It is worth noting that older patients infected by COVID-19 can present with an altered mental status but no fever because of a deranged immune response (Ward et al, 2020).

It is important that paramedics are aware of the wide array of symptoms of the disease and that no single sign or symptom is accurate for ruling COVID-19 in or out.

Influenza viruses

There are three main types of influenza viruses that can infect humans—types A, B and C—and cause seasonal influenza (Du et al, 2021). The average incubation period for all influenza viruses is 1–4 days (Solomon et al, 2020)^, and influenza B has a shorter incubation period of an average 0.6 days (Lessler et al, 2009).

The differences in the incubation period and time from exposure to symptoms onset could be early indicators to distinguish between seasonal influenza and COVID-19 (Pormohammad et al, 2021) before confirmation from diagnostic tests.

Influenza A can be divided into subtypes based on two surface proteins, haemagglutinin (H) and neuraminidase (N), and influenza subtypes are named according to the composition of these surface proteins (for example, H3N2 and H1N1), while influenza B viruses are mainly separated into two genetic lineages (Krammer et al, 2018).

Influenza viruses enter a person through epithelial cells in the trachea, bronchi and bronchioles and this causes lung inflammation (Kalil and Thomas, 2019), which can lead to swelling in the respiratory tract and excessive mucus production.

Key features of influenza include headache, lethargy, loss of appetite and upper respiratory symptoms (e.g. sore throat, non-productive cough and sneezing) (Krammer et al, 2018). These are very similar to symptoms of other ILIs which can make a diagnosis of influenza difficult.

Individuals aged <2 years and >65 years, pregnant women, immunosuppressed and obese individuals, and people with chronic lung disease, cardiac disease, advanced liver disease or chronic kidney disease, and nursing home residents and smokers are all at a higher risk of severe disease (Krammer et al, 2018).

Severe complications of influenza include acute pneumonia, ARDS, sepsis, Guillain-Barré syndrome, rhabdomyolysis, myocarditis, pericarditis, meningitis and encephalitis (Collins et al, 2013).

Respiratory syncytial virus

RSV is an RNA virus belonging to the Pneumoviridae family (Collins et al, 2013) and is the most dominant cause of respiratory tract infections in children (Barr et al, 2019). The incubation period for RSV is 4–6 days, with a median incubation period of 4.4 days (Lessler et al, 2009).

Patients with RSV often present with fever, coughs, breathing difficulties, asthma exacerbations, pneumonia or bronchiolitis (Barr et al, 2019) which are again very similar to other ILIs and common winter respiratory infections.

Although healthy adults with an RSV infection often experience only mild symptoms, children aged <2 years are more at risk of serious complications and 2–6% of children with RSV will require management in a paediatric intensive care unit (Green et al, 2016).

Additionally, people with heart, lung and immunocompromising diseases and older patients are also at a high risk of developing serious complications (Aujard and Fauroux, 2002).

Parainfluenza

Parainfluenza (PIV) is an RNA virus with an incubation period of 1–7 days and four serotypes (PIV-1, PIV-2, PIV-3 and PIV-4) (Centers for Disease Control and Prevention (CDC), 2019).

The median incubation period is 2.6 days (Lessler et al, 2009). Parainfluenza infection normally starts in the epithelium of the upper respiratory tract and spreads to the paranasal sinuses, larynx, bronchi and eustachian tubes (Schomacker et al, 2012).

Serotypes 1 and 2 are linked with croup and 3 with bronchiolitis, bronchitis and pneumonia, serotype 4 is detected less often (CDC et al, 2019).

Healthy adults generally experience mild symptoms such as cold symptoms, rhinorrhoea, coughs and sore throats. However, infection can trigger an exacerbation of underlying conditions in patients with chronic respiratory symptoms, such as asthma and chronic obstructive pulmonary disease (COPD) (Russell and Ison, 2017).

Furthermore, young children are at a higher risk because of their small airways and immature immune systems (Schomacker et al, 2012) and older people in nursing homes have an increased risks of serious complications of parainfluenzas (Lynch and Kajon, 2016).

Rhinovirus and adenovirus

There are more than 100 types of rhinovirus and adenovirus that can cause the common cold (Lynch and Kajon, 2016; To et al, 2017), with a range of symptoms including rhinitis and cough, to fevers, bronchitis, pneumonia, conjunctivitis and gastroenteritis.

A significant proportion of individuals can be asymptomatic (Ortega et al, 2021) and, interestingly, adenovirus can sit latently in those previously infected and reactivate at a later time (Dela Cruz et al, 2019).

As with other ILIs, young children, older people, people who are immunosuppressed and those with underlying health problems are more likely to experience severe complications (To et al, 2017).

Self-management and symptom control

Self-management and symptom-relieving treatment for ILIs include encouraging individuals to drink adequate fluids to avoid dehydration, rest if they feel ill and fatigued (which could be for up to a week), take paracetamol/ibuprofen to reduce discomfort and fever, take a cough suppressant or a natural remedy (such as honey) to reduce coughs, and use corticosteroid and/or bronchodilators to reduce wheeze and manage breathlessness (Hall, 2001; Section on Clinical Pharmacology and Therapeutics, 2011; Jefferson et al, 2014; NICE, 2020; 2021; PHE, 2008; 2021c).

Antivirals

Antivirals should be considered for some patients in at-risk groups with RSV, SARS-CoV-2 and influenza A or B infections when the UK national surveillance scheme indicates that influenza is circulating in the community (Hall, 2001; PHE, 2008; 2021c; NICE, 2009; 2020; 2021; Jefferson et al, 2014) as they reduce the likelihood of death by 25% among hospitalised individuals (Bernardo et al, 2019).

However, the routine use of antivirals for all ILI patients should be discouraged as evidence has shown that previously healthy patients with ILI treated with an antiviral (oseltamivir) recover only one day earlier than to those managed with usual care only (Butler et al, 2020).

Clinicians should consider the small benefits of antiviral use, the difficulty of diagnosing ILIs accurately, the risks of antimicrobial resistance, possible side-effects (such as nausea and vomiting) and financial costs in their clinical decision-making process for prescribing or administering antivirals (Michiels et al, 2013; Jefferson et al, 2014).

Antibiotics

It is possible that an ILI could lead to the development of secondary complications including bacterial infections of the respiratory tract, namely pneumonia, bronchitis and otitis media in children (Low, 2008). However, the prevalence of bacterial co-infection is not as high as one may presume. Klein et al (2016) summarised that, in the majority of the research included in their meta-analysis, the presence of bacterial co-infection with influenza was between 11% and 35%.

This would suggest that it would not be appropriate for clinicians to assume all patients are co-infected and routinely prescribe antibiotics, as this may increase the risk of antibiotic resistance (Jefferson et al, 2014). However, a recent review by Dolk et al (2018) suggests that almost half of all antibiotics prescribed in primary in the UK were for respiratory tract infections, which provide little benefit for acute respiratory tract infections (including ILIs) when pneumonia is not suspected (Michiels, 2008; Little et al, 2013; Dolk et al, 2018).

Routine use of antibiotics in patients presenting with ILI should be discouraged unless there is a clear indication of secondary bacterial respiratory tract infection and/or pneumonia.

COVID-19 testing

If a patient presents with ILI symptoms and/or a COVID-19 symptom (e.g. fever, persistent cough or loss of taste or smell), it is recommended that a SARS-CoV-2 diagnostic sample be obtained and sent for laboratory testing. This should be done using a RT-PCR test as rapid lateral flow tests were designed for the detection of asymptomatic COVID-19 carriers so may give a false negative result (poor sensitivity). The RT-PCR test is the gold standard for the diagnosis of COVID-19 (Department of Health and Social Care, 2020).

Consider admission to hospital

Most patients with ILIs can be safely managed in the community or ambulatory care. If your patient develops complications of influenza (such as acute bronchitis), exacerbation of existing respiratory conditions such as asthma or COPD, pneumonia, febrile convulsion or encephalomyelitis) or presents with signs of sepsis, haemoptysis, cyanosis or increased work of breathing or if an alternative diagnosis is suspected, refer to acute hospital urgently for further investigation.

Consider a lower threshold for admission if a patient is in one of these at-risk groups: patients with chronic medical conditions (such as chronic respiratory disease, heart disease, renal disease, liver disease or neurological conditions or diabetes), people who are immunocompromised, people aged 65 years or older and children aged under 2 years as they are more likely to develop severe complications from ILIs.

Hand hygiene

Hand hygiene is an effective way to prevent transmission of ILIs by direct contact and it has been one of the key interventions recommended by UK and international health agencies to prevent the transmission of COVID-19 (WHO, 2020; 2021; PHE, 2021d; CDC, 2021). The best way to achieve hand hygiene is to wash the hands with soap and water; alternatively, clinicians can clean their hands by rubbing them with alcohol-based sanitiser, as those with 60–80% alcohol content have been shown to be effective against a range of viruses and bacteria, including pathogens that cause respiratory infections (Grayson et al, 2009).

Personal protective equipment

Together with the Association of Ambulance Chief Executives, the UK Health Security Agency (UKHSA) (2021) continues to recommend the routine use of level 2 PPE (including disposable gloves, disposable apron, fluid-repellent (type II-R) surgical masks and eye protection) for all patients, regardless of their symptoms, during the pandemic.

These offer sufficient protection to staff while they are dealing with patients with ILI symptoms where the modes of transmission are practically the same as COVID-19.

Furthermore, if there is a high risk of exposure to aerosols (i.e. when carrying out aerosol-generating procedures), level 3 protection, including FFP3 masks, should be used as per current guidance (UKHSA, 2021).

Environmental cleaning and disposal of clinical waste

Significant numbers of ILI pathogens can survive on a contaminated surface for hours or longer (Ikonen et al, 2018). Therefore, environmental cleaning (especially of frequently touched surfaces) and appropriate disposal of clinical waste are both vital to prevent indirect contact and fomite transmission of ILIs.

Exclusion from school/workplace

Patients with suspected ILIs should be advised to keep away from school or the workplace during the infectious period to minimise the risk of further transmission. Different respiratory illnesses have different infectious periods and, in general, infectiousness is greatest in the early stages of infections (Richardson et al, 2001). As a general rule, patients should be excluded from school or their workplace for at least 24 hours after fever and respiratory symptoms have resolved; this may be longer for specific diseases (PHE, 2016).

Vaccination

Vaccinations are available for some respiratory pathogens that cause ILIs (PHE, 2020b). Paramedics and other ambulance clinicians are encouraged to receive appropriate vaccines (such as seasonal influenza and COVID-19 vaccines) for themselves and to be an advocate for vaccinations to encourage their patients to receive them.