Target Organisms

The viruses listed below are relevant to the indoor environment. These viruses can contaminate indoor air and/or surfaces, and have the potential to cause serious illness. This is not an exhaustive list. If you wish to test your product against a particular virus, please contact us to discuss feasibility. Surrogate viruses are used in place of viruses that cause severe infections as detailed below.

Influenza A (H1N1), part of the Orthomyxoviridae family, is a single-stranded RNA enveloped virus ranging from 80-120 nm in diameter. Influenza A virus is responsible for many epidemics of respiratory illness, including the swine-flu epidemic of 2009. Associated with increased rates of hospitalisation and death in susceptible individuals, influenza viruses are spread from person-to-person via large virus-containing droplets and aerosols produced by coughing, sneezing or talking. Influenza viruses may also be spread via contaminated fomites or by direct contact. At airmid healthgroup, we have validated the use of Influenza A (H1N1) virus in virus removal and inactivation studies performed in environmental test chambers or in the laboratory, depending on your requirements.

Influenza A (H3N2) analogously to H1N1 subtype is part of the Orthomyxoviridae family and is a single-stranded RNA enveloped virus ranging from 80-120 nm in diameter. This influenza subtype circulates in pigs and it was first identified in humans in 2011. It has caused a few outbreaks and is sporadically detected in people with a history of direct contact with swine. Human to human transmission is possible. H3N2 typically causes flu-like symptoms, which can result in hospitalisation and possibly fatalities. 

Rhinovirus, part of the Picornoviridae family, is a small single-stranded RNA non-enveloped virus around 27 nm in diameter. Rhinovirus is among the most common viral infective agents in humans and accounts for more than 80% of common colds. The main routes of transmission of Rhinovirus are via aerosols, droplets and by direct contact with infected individuals or via indirect contact from contaminated surfaces or fomites. At airmid healthgroup, Rhinovirus has been validated for use in virus removal studies based in the environmental test chamber or laboratory, depending on the testing requirements of our clients.


Norovirus is a single-stranded RNA non-enveloped virus 38-40 nm in diameter, is part of the Caliciviridae family.  Commonly known as the vomiting bug, norovirus is recognised as the cause of 90% of epidemic non-bacterial outbreaks of gastroenteritis around the world. It is highly contagious with multiple modes of transmission including via faecal-contaminated food or water, person-to-person contact, aerosol droplets or fomites. It is relatively stable in the environment and is resistant to disinfectants. As Norovirus does not adapt well to cell culture, and owing to its contagious nature, surrogates of the virus are commonly used. Feline Calicivirus (FCV), also part of the Caliciviriadae family is widely used as a surrogate for Norovirus. At airmid healthgeroup, FCV has been validated as a Norovirus surrogate for use in virus removal studies based in the environmental test chamber or test duct and laboratory, depending on our clients, testing requirements.

Human coronavirus 229E (HCoV-229E) is an enveloped, positive-sense, single-stranded RNA virus, ranging from 80 to 150 nm in diameter. It is one of the seven human coronaviruses and belongs to the genus Alphacoronavirus. HCoV-229E is ubiquitous and it is recognised as one of the main causes of the common cold. The upper respiratory tract infection can also exacerbate asthma or cause bronchiolitis and pneumonia. Analogously to other coronaviruses, it has been shown that HCoV-229E is capable of invading neural cells and hence manifesting with neurological symptoms and signs.
Murine Hepatitis virus is a type of murine coronavirus (M-CoV) that was first isolated in 1947 in rodents. It belongs to genus Betacoronavirus and  is a positive-stranded single-strand, enveloped RNA virus with a diameter of 80-90 nm. Although contagion to human population has not been registered, the virus is highly infectious and is mainly transmitted through aerosols and direct contact. It is the most studied coronavirus in animals other than humans, and has been used as an animal disease model for many virological and clinical studies. Murine coronavirus is believed to be most closely related to human coronavirus HKU1.
Enterovirus 71 (EV71) belongs to the Picornaviridae family, and is a small (20-30 nm), non-enveloped virus with a single-stranded positive-sense RNA genome. EV-71 can cause mild illness such as hand, foot, and mouth disease in children or occasionally it can induce severe neurologic disease such as encephalitis, meningitis and acute flaccid paralysis. Large outbreaks of EV71 make this virus a possible major public health issue. Being present in stool and in the oropharyngeal tract, enteroviruses spread from person-to-person by faecal transmission and by respiratory droplets.
Vaccinia virus  is a linear, double-stranded DNA virus, belonging to the Poxviridae family.  The virion is enveloped, ovoid or brick-shaped, 220-450 nm long and 140-260 nm wide. The vaccinia virus is the source of the modern smallpox vaccine and it was used to eradicate smallpox in a global vaccination campaign in 1958–1977.. The virus spreads via respiratory droplets, direct contact or fomites. The infection causes cold-like symptoms and cutaneous lesions characterised by serous and purulent discharge, ulceration and necrosis. Vaccinia virus is studied widely for laboratory research and clinical studies.

Adenovirus is part of the Adenoviridae family and is a non-enveloped double-stranded DNA virus of 75 nm diameter. Adenovirus infections play a major role in most major respiratory disease syndromes in children under 6, causing laryngitis, croup, bronchitis, bronchiolitis, pertussis-like syndromes and pneumonia (also conjunctivitis and diarrhoea). Adenovirus can be spread from an infected person to others via direct contact, from their coughing or sneezing or via touching contaminated surfaces. The virus can be shed by infected individuals in the faeces for months after recovery.


Respiratory Syncytial Virus of the Paramyxoviridae family, is a single-stranded RNA enveloped virus 80-350 nm in diameter. RSV causes mild cold-like symptoms in adults but can cause airway infections (e.g. bronchiolitis and pneumonia) in infants and young children. The virus is spread via tiny droplets in the air after an infected person coughs or sneezes. It can also be transmitted by direct contact with an infected person or via contaminated surfaces such as door knobs or toys.

Human Parainfluenza Virus (HPIV) is part of the Paramyxoviridae family and is a single-stranded RNA enveloped virus approximately 200 nm in diameter. HPIV causes upper or lower respiratory tract infections, usually with mild symptoms. However HPIV can cause more severe lower respiratory illness such as croup or pneumonia in young children and older adults. Similar to Rhinoviruses, HPIV is transmitted via aerosols, direct contact with infected individuals or via indirect contact from contaminated surfaces or fomites.


Feline calicivirus (FCV), a small (30-40nm), unenveloped RNA virus, is one of the most common viral pathogens of cats. It belongs to the family Caliciviridae which includes other significant pathogens of man and animals. As an RNA virus, FCV has a high elasticity of its genome, which makes it more adaptable to environmental pressures. The virus attacks the feline respiratory tract, mouth, intestines and the musculoskeletal system. It is highly communicable in unvaccinated cats, and is commonly seen in multi-cat facilities, shelters, poorly ventilated households and breeding catteries. The virus is readily transmitted between cats through direct contact with infected saliva, inhalation of sneeze droplets, sharing of food and a contaminated environment. Because of the similarity of FCV to norovirus, a common cause of gastroenteritis in humans, FCV has been used as a surrogate for it in research. It is also used in general Caliciviridae research due to its being one of the few of that group of viruses that grows well in vitro.

Human coronavirus OC43 (HCoV-OC43) is an enveloped, positive-sense, single-stranded RNA virus, 80-120 nm in diameter and it belongs to the genus Betacoronavirus.  HCoV-OC43 is one of seven coronaviruses known to infect humans. Similarly to other human coronaviruses, HCoV-OC43 can cause common cold and mild illness or severe respiratory tract infections, including pneumonia and bronchiolitis. HCoV-OC43 infection can cause neurologic al symptoms too. It is believed that this virus is responsible for the 1889–1890 pandemic, historically know as Russian flu.

Bacteriophage MS2 has been used as a surrogate virus in numerous studies of virus contamination of air, water and food because MS2 mimics the behaviour of pathogenic viruses while being harmless to humans and animals. MS2 (Leviviridae family) is a bacteriophage that specifically infects Escherichia coli and is a non-enveloped single-stranded RNA icosahedral virus with a diameter of 25-27 nm. MS2 is similar in morphology to Picornoviruses and can persist as an infectious virus in the environment comparable with the most resistant human pathogens in the Picornoviridae family e.g. poliovirus, rhinovirus and enterovirus. Based on these characteristics it is an ideal surrogate for small enteric viruses and has been validated for use at airmid healthgroup.

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