H Letter

What is it?

Haemophilus influenzae is a type of bacteria that can live in a person’s nose and throat. It is considered part of the normal flora of the nasopharynx (upper respiratory tract) and generally does not cause symptoms of disease. However, when the bacteria invade other areas of the body, severe infections and complications can occur. Encapsulated strains of haemophilus influenzae (bacteria with distinct polysaccharide capsules) are more likely to cause invasive infections than non-encapsulated subtypes (those without polysaccharide capsules). Of the 6 encapsulated subtypes (named A-F), type B (Hib) is the only vaccine–preventable strain.  

What to look for

The symptoms of an invasive Hib infection will depend on the location of the infection (e.g., brain, lungs). 

Meningitis (brain inflammation) is the most common presentation of an invasive Hib infection and is often accompanied by bacteraemia (blood infection). Invasive infections can also manifest as otitis media (ear infections), epiglottitis (swelling of the throat), pneumonia (lung infections), arthritis (joint infection), cellulitis (skin infection), osteomyelitis (inflammation to the bone) and pericarditis (inflammation to the sac surrounding the heart).  

Even with treatment, 3% of Hib meningitis cases occurring in developed countries will be fatal, and 10-30% of cases will have permanent neurological complications.  

How can it be transmitted?

Hib can be passed from person to person through inhaling the respiratory droplets of an infected person (produced from coughing or sneezing). In some instances, it can also be transmitted by direct contact with infectious secretions (e.g., touching nasal mucous on a tissue or surface). 

Carriers may be symptomatic or asymptomatic. A person can transmit the bacteria for as long it is present in the nasopharynx. 

Epidemiology

Before vaccination was included on the National Immunisation Program (NIP) in 1992, Hib was the biggest cause of invasive bacterial infection in children in Australia. Since then, the number of Hib infections notified has reduced by 95%. 

Aboriginal and Torres Strait Islander children have a much greater burden of disease than the non-Indigenous population.  

Asplenia and hyposplenia are conditions associated with a lifelong risk of bacterial infections. Individuals with these conditions are therefore at a greater risk of invasive disease if they have not been appropriately immunised. 

Prevention

Protection is offered through the intramuscular administration of inactivated, conjugate vaccines (combination and single antigen vaccines). They are provided on the NIP at: 

• 6 weeks, 4 months, and 6 months- Infanrix® hexa/Vaxelis® 
• 18 months- ActHIB®  

NB: Children <5 years of age with asplenia and hyposplenia should be up to date with the routine schedule and if not, they should be offered catch-up. Those aged 5 years and over who did not complete their primary course of vaccination should receive a single dose of Hib-containing vaccine. 

Vaccine side effects

Injection site reactions and fever have been reported following administration of Hib-containing vaccines. Symptoms usually appear within the first 4 hours and resolve within 24 without the need for intervention or additional monitoring. 

Resources

• MVEC: Asplenia and hyposplenia
• Australian Immunisation Handbook: Haemophilus influenzae type b (Hib)
• Australian Government Department of Health and Aged Care: Changes to the National Immunisation Program schedule from July 1 2023

Drive-through immunisation clinics are an alternative venue for supporting vaccine delivery. A drive-through clinic can assist members of the community to continue to receive recommended immunisations whilst maintaining physical distancing.

A drive-through clinic may not be a setting that is recommended for all patients. It is important that patients be screened for their suitability to use a drive-through service prior to immunisation. Pre-screening of patients can identify previous immunisation reactions, history of vasovagal reactions or needle phobia.

Running sessions by appointment may allow for planning the type and amount of vaccines required and also allows the flow of patients to be staggered in order to prevent traffic congestion.

Preparation for drive-through clinics

There are many different factors that need to be considered when setting up for this type of immunisation venue.

The location

Consider a location within close proximity of the GP service or health care facility (if applicable). An ideal location would allow for a 1-directional flow of traffic in order to avoid congestion and ensure the safety of roaming staff members. Each individual parking bay should allow enough room for all 4 car doors to completely open without any obstructions (to ensure full access to each patient should AEFI occur).

Equipment

Carefully consider the equipment required to set up and maintain a drive-through clinic. Equipment should include clear signage, bed/chair to manage adverse events if required, an anaphylaxis response kit, essential paperwork, (such as pre-immunisation checklists and vaccine side effects forms), equipment to maintain the cold chain, as well as any equipment necessary to prepare and administer vaccines. Remote access to patient records and the Australian Immunisation Register (AIR) is recommended to allow for review of immunisation records. as well as appropriate documentation of any vaccines administered.

Staff

Staff may include nurse immunisers, as well as medical and administrative personnel.

The cold chain

Storage of vaccines in a drive-through clinic setting must comply with the cold chain recommendations set out by the vaccine manufacturer.  The time between vaccines being removed from purpose-built vaccine fridges to being administered should be as short as possible.

During a drive-through immunisation session

Immunisation history, pre-immunisation checklist, possible vaccine side effects and suitability for immunisation must be reviewed and discussed prior to vaccination.

Emergency equipment (anaphylaxis response kit) and a telephone must be readily available should they be required.

Correct injection technique is essential, ensuring that the entire limb is exposed and correct anatomical landmarks identified to locate the correct injection site. If a patient cannot be safely immunised in the car (eg: child seated in the middle car seat) or is not a suitable candidate for in-vehicle immunisation then they could be immunised out of the car in a chair, then returned to the car to wait for the recommended 15 minute waiting period. Patients should be advised not to get in and out of their cars whilst parked.

Post-immunisation in a drive-though session

Following immunisation, patients must remain at the vaccination venue for at least 15 minutes and should be advised to avoid driving for at least 15 minutes following vaccination. Patients waiting in their vehicles should be instructed to use the car horn to gain attention in their 15 minute observation period if required. All vaccines should be recorded on the AIR and appropriate documentation should be completed and provided to the patient.

Resources

• MVEC: Cold chain
• MVEC: Shoulder Injury Related to Vaccine Administration
• MVEC: Shoulder Injury Related to Vaccine Administration (SIRVA) eLearning package
• National Vaccine Storage Guidelines ‘Strive for 5’
• MVEC: Administration of injected vaccines- correct technique
• ATAGI Clinical Statement on Vaccination Observation Time
• ATAGI statement on considerations for establishing drive-through COVID-19 vaccination clinic sites

A hypotonic-hyporesponsive episode (HHE) is defined as the sudden onset of hypotonia (muscle limpness), reduced responsiveness or unresponsiveness and pallor or cyanosis occurring after vaccination in early childhood (< 2 years of age).

Most children are initially irritable and febrile prior to the event and respiration may be shallow during the event. HHE’s can be immediate or delayed. The immediate HHE’s are often preceded by crying, breath holding and are like an immediate vasovagal phenomenon. Close inspection is required to ensure there are no features suggestive of an allergic reaction. The delayed reactions usually occur 1 to 48 hours after vaccination and resolve spontaneously; the median episode duration is 6-30 minutes. Diagnosis of HHE is made clinically and often no investigations are required.

This occurs where no other cause is evident, such as seizure or anaphylaxis. This is distinguished from a vasovagal-syncope (fainting episode), which presents with similar signs and symptoms but occurs soon after vaccination (< 5mins) and usually occurs in an older age group (≥ 2 years of age).

The pathogenesis of HHE is unknown but is likely to be multifactorial. HHE is rare and results in transient signs, and hence, there are limitations to investigation.

Associations and incidence

HHE has been documented to occur after immunisation with all vaccines, but historically had been most associated with whole-cell pertussis vaccines in early infancy. There has been a decreased incidence following the change from whole-cell pertussis to acellular pertussis vaccines.

HHE has been observed mainly after the first doses of vaccines at 6 to 8 weeks of age.

In Australia during 2012, 2.2 cases of HHE were reported per 100,000 doses of pertussis-containing vaccine given to children <1 year of age.

Treatment

These episodes self-resolve and often don’t need any treatment. However, the initial management should be for shock and include assessment of airway, breathing and circulation. Careful clinical observation and documentation of the event are vital for differential diagnosis. Urgent medical review is advised for paediatric assessment and to exclude other causes.

Implications and considerations for future vaccines

HHE is not a contraindication to further doses of vaccines, including pertussis containing vaccines.

The recurrence rate for a further HHE is 3.5% [refer to Resources]. No long term sequelae have been identified in the small number of children who have had long term follow-up.

The next scheduled immunisations may need to be given under medical supervision, this can be arranged by contacting the vaccine safety service in your state.

Any adverse event following immunisation (AEFI) in Victoria should be reported to SAEFVIC.

Resources

• Hypotonic-Hyporesponsive Episode – A SAEFVIC Case Study July 2017
• Vaccine: Hypotonic-hyporesponsive episode (HHE) as an adverse event following immunization in early childhood: Case definition and guidelines for data collection, analysis, and presentation
• Paediatrics: Hypotonic-hyporesponsive episodes reported to the Vaccine Adverse Event Reporting System (VAERS) 1996 -1998
• Australian Immunisation Handbook: After vaccination
• Vaccine: Recurrence risk of a hypotonic hyporesponsive episode in two Australian specialist immunisation clinics

What is it?

Human papillomavirus (HPV) is a double stranded DNA virus that can infect both men and women. It can affect a person’s anogenital or respiratory tract. There are more than 100 known sub-types of HPV, with 40 of them affecting the anogenital region.

What to look for

Most people infected with HPV show no acute clinical symptoms at all however infection can progress to have significant health impacts or diseases such as cancer.

HPV subtypes 6, 11, 40, 42, 43, 44, 54, 61, 70, 72, 81 and 89 are associated with the development of lesions such as genital warts, cutaneous warts and respiratory papillomatosis (wart-like lesions in the respiratory tract). Respiratory papillomatosis is characterised by warty growths within the respiratory tract which can lead to airway occlusion and can be fatal in severe cases.

Types 16, 18, 31, 33, 35, 45, 52 and 58 are oncogenic (cancer causing) strains of HPV and are associated with cancers of the cervix, vulva, vagina, penis, anus, oral cavity and oropharynx. Australian data from 2005-2015 has shown that 77% of all cervical cancers were associated with infections with either HPV-16 or HPV-18.

How is it transmitted?

HPV is a highly contagious virus that is transmitted through different forms of intimate contact. With infections often asymptomatic, people often do not know they are carriers and can unknowingly transmit the virus to others.

Genital HPVs are transmitted through sexual contact. Risks of exposure to HPV can be related to the number of sexual partners a person has had. Condoms can reduce the risk of transmission of genital HPVs, however, do not eliminate risk entirely.

Infected mothers can transmit the virus to their newborn during delivery resulting in oral HPV infections in the newborn. In some cases, this can lead to the development of respiratory papillomatosis.

Epidemiology

Surveillance of HPV infections is complicated due to the majority of infections being asymptomatic. It is estimated that up to 90% of the population will be infected with at least one type of HPV at some point in their lives. Cervical cancer is the fourth most common cancer affecting women globally.

Immunocompromised individuals, in particular those with HIV, and men who have sex with men (MSM) are at higher risk of HPV infection and developing HPV-related cancers.

Prevention

Vaccination can provide protection against HPV infection and the development of HPV-related lesions and cancers. It is ideally administered prior to a person becoming sexually active.

There are 2 vaccines available in Australia:

• Cervarix®- 2vHPV recombinant vaccine protecting against types 16 and 18
• Gardasil®9- 9vHPV recombinant vaccine protecting against types 6, 11, 16, 18, 31, 33, 45, 52 and 58.

Gardasil®9 is funded on the National Immunisation Program (NIP) as a single dose for immune competent males and females in Year 7 (or age equivalent) primarily through the school-based program. A funded catch-up program is also available for individuals ≤ 26 years of age.

ATAGI further recommends that males ≥ 26 years of age who are at high risk of disease, as well as immunocompromised individuals of any age, are also vaccinated. Gardasil®9 is registered for use in both males and females up to the age of 45 years. Cervarix® is registered for use in females only up to 45 years of age.

Immunocompromised individuals of any age and immune competent individuals 26 years of age and over require a 3 dose schedule in order to be optimally protected. Doses should be administered at 0, 2 and 6 months.

Side effects

HPV vaccination is generally well tolerated with mild side effects such as fever, nausea, headache, dizziness and fatigue commonly occurring in the first 24-48 hours.

Syncope (fainting) is also commonly reported in the adolescent population however is likely associated with the process of vaccination rather than the vaccine itself. Anyone prone to syncopal episodes should lay down for 15 minutes before during and after the vaccination process to minimise the risk of injury due to falls.

Commonly asked questions

• Hepatitis B is an infection caused by the hepatitis B virus resulting in jaundice, nausea, vomiting, pain and fever.
• Disease is transmitted via blood and body fluids of an infected person.
• Initial hepatitis B infection can often be asymptomatic, meaning a person may be unaware that they are carrying the infection.
• Following the acute infection, up to 10% of those infected in adulthood, and up to 90% of those infected in infancy will become chronically infected.
• Chronic infection with hepatitis B virus can lead to end stage liver failure (cirrhosis) and hepatocellular carcinoma.

Prevention of hepatitis B infection

• Hepatitis B vaccine is currently provided for free on the National Immunisation Program (NIP) at birth (within 7 days), 6-weeks, 4-months and 6-months.
• A single booster dose is also funded at 12-months of age for those who are born at < 32-weeks gestation and/or < 2000 grams [See MVEC: Preterm Infant Immunisation]
•  Hepatitis B vaccination is also funded in Victoria for additional at risk groups:
  • Aboriginal and Torres Strait Islander people
  • Household contacts or sexual partners of people living with hepatitis B infection
  • People who inject drugs or are on opioid substitution therapy
  • People living with hepatitis C
  • Men who have sex with men (MSM)
  • People living with HIV
  • Prisoners and remandees
  • People who are no longer in a custodial setting but did not complete the vaccine course while in custody
  • People from endemic countries who arrived in Australia in the last 10 years
• Certain occupations (including those directly involved in patient care and/or the handling of human tissue, blood or body fluids) also carry an increased risk of exposure to hepatitis B virus. In these instances the vaccine is recommended but not funded on the NIP.

Serological testing

• Performing hepatitis B serology following hepatitis B vaccination is not routinely indicated.
• Post vaccination screening, carried out 4-weeks after the final vaccine dose, is recommended for those at significant occupational risk (eg health care workers), those at risk of severe complications of hepatitis B disease (eg immunocompromised, those with pre-existing liver disease), those in whom poor immune response may occur (eg impaired renal function) and sexual partners and household contacts of people living with hepatitis B.
• If serology is performed more than 8-weeks post the final vaccination dose, results may be considered less reliable.
• Serology should be performed every 12-months in patients with impaired renal function +/- dialysis regardless of previous serological testing [see Table 1].

Patients with impaired renal function

• Patients with impaired renal function +/- dialysis are at increased risk of hepatitis B infection. In addition they often have a diminished immune response to the hepatitis B vaccine. The cause of this is not completely understood. It is well documented that the earlier a patient is immunised in the disease progression, the better the response and more long term protection they will have.
• Impaired renal function is defined as chronic kidney disease (CKD) 4-5 (GFR < 30ml/min)
• Some patients with impaired renal function may progress to a renal transplant [MVEC: Solid organ transplant recipient]
• There is evidence to suggest that by vaccinating patients with impaired renal function with a combination hepatitis A and B vaccine (Twinrix® Adult 720/20), seroconversion can be enhanced [see Table 1].
• If immune response remains sub-optimal following the immunisation recommendations in Table 1, please refer to the below recommendations for management of non-responders to hepatitis B vaccination.

Table 1: Recommended vaccine schedule for those with renal impairment using combined hepatitis A and B vaccine [Twinrix® Adult 720/20]

# Twinrix® Adult (720/20) is a combination Hepatitis A and B vaccine. It contains 720 ELISA units of HAV antigens and 20mcg of Hepatitis B surface antigen protein. Each dose is 1.0ml given intramuscularly

Non-responders to hepatitis B vaccination

• A non-responder to hepatitis B vaccination is any person with a documented age-appropriate vaccine history, who has a current Anti-HBs level of <10m lU/mL 4-8 weeks following the final vaccine dose.
• MVEC recommends the following immunisation pathway for all non-responders: MVEC pathway for routine intramuscular (IM) hepatitis B vaccine non-responders ≥ 12-months of age
• Persistant non-responders should be informed of their immune status and advised to minimise exposures.
• Hepatitis B immunoglobulin may be given to non-immune persons within 72 hours of exposure to prevent infection.

Reference

• Tung J, Carlisle E, Smieja M, Kim PT, Lee CH. A Randomized Clinical Trial of Immunization With Combined Hepatitis A and B Versus Hepatitis B Alone for Hepatitis B Seroprotection in Hemodialysis Patients. Am J Kidney Dis. 2010;56(4):713-9.
• Playford EG, Hogan PG, Bansal AS, Harrison K, Drummond D, Looke DF, Whitby M. Intradermal recombinant hepatitis B vaccine for healthcare workers who fail to respond to intramuscular vaccine. Infection Control and Hospital Epidemiology 2002 Feb;23(2):87-90
• Australian Immunisation Handbook- Hepatitis B
• MVEC pathway for routine intramuscular (IM) hepatitis B vaccine non-responders ≥ 12-months of age
• The Australian Immunisation Handbook: hepatitis B chapter
• Better Health Channel: hepatitis B
• DHHS: Immunisation schedule Victoria and vaccine schedule eligibility criteria
• MVEC: Solid organ transplant recipient
• MVEC: Preterm infant immunisation
• RCH clinical practice guidelines: Needle stick injury