KEY POINTS:
Here we go again. From September 1, teenage girls aged 16 to 18 can rock up to their GP to be vaccinated for free against human papilloma virus (HPV), an infection transmitted from sexual contact. It can be a silent killer, lingering undetected for years before developing into cervical cancer. About 160 New Zealanders a year develop cervical cancer and 60 die.
Next year, the free shot will be available in intermediate schools for girls aged 11-13 and in secondary schools for senior students, with their parents' consent.
The new vaccine, Gardasil, is at least 97 per cent effective against the two HPV strains responsible for about 70 per cent of cervical cancers, clinical trials have found.
A cancer-preventing vaccine vouched to be that effective is, to use medical parlance, hot. Prime Minister Helen Clark is an enthusiastic supporter, committing $177 million in funding over five years, allowing a pre-election roll-out.
Another new-generation vaccine is being pumped into babies at health clinics. Prevenar immunises against strains of pneumococcal bacteria which can lead to pneumococcal meningitis, blood poisoning, pneumonia and other infections. Rates are high among Maori and Pacific Island children and about 150 children had severe forms of the infection in 2006. Government agency ESR estimates the vaccine could reduce cases in the under-5s by about 80 per cent. This should in turn reduce the chances of their grandparents catching pneumonia.
But there are doubters. Prevenar's effectiveness has been questioned in the United States by critics who claim doctors involved in clinical trials had a conflict of interest. Still in the US, reports of extreme adverse reactions in Gardasil have been making headlines. Early this month, Diane Harper, an American doctor who helped develop the vaccine, was on National Radio calling the US vaccination programme aimed at young girls "a great big public health experiment" (see story below).
Auckland-based consumer group Women's Health Action has called for the HPV programme to be postponed pending a full review of the information so "young women and their parents are fully informed about the vaccine and what it actually offers them".
Campaigner Lynda Williams says the group has doubts about how long the vaccine will last. She is also concerned it will breed complacency, leading women to skip regular smear tests, she told a seminar marking the 20th anniversary of the Cartwright inquiry.
Here we go again. Debate over the effectiveness of vaccines flared again last month when Auckland University experts' findings that the $220 million MenzB vaccine was no longer protecting most children were reported in the Herald. The Ministry of Health says research it commissioned from Victoria University says the opposite.
The highly publicised MenzB campaign was shelved in April, largely because the epidemic was under control but also because the vaccine might not be compatible with Prevenar, the pneumococcal vaccine which became available in June. The addition of Gardasil and Prevenar to the immunisation schedule mean infants now face 10 vaccinations before the age of 5 and four more at ages 11 and 12 (Gardasil is given in three doses over a 6-month period).
Trials are continuing for a new vaccine covering the spectrum of type B meningococcal strains. Also in the wings is a vaccine for type A meningococcal disease. Public health experts predict a wave of new vaccines in the next few years which will prevent specific cancers.
Will these vaccines be safe? Will they work? Or are we, as some immunisation critics maintain, victims of multinational drug companies inveigling themselves with government agencies who err on the side of caution. To them, caution means protecting mass populations rather than individuals.
Vaccinations can be unpleasant. The needle hurts. There are anecdotal stories of children experiencing much nastier reactions than common swelling or feeling unwell _ to which the standard medical response is that there was no causal link.
Ministry of Health officials have a way of marginalising immunisation critics. They can't help it _ the critics may be vocal but they are few in number and the officials have the weight of clinical trials, and most doctors, behind them. They also hint that their adversaries have ideas which are "out there" or "weird".
But the medical fraternity can never guarantee that vaccines are 100 per cent safe or 100 per cent effective.
One problem is ignorance (or short-term memory). Most parents lack more than a sketchy knowledge of the diseases on the immunisation schedule. Serogroup B meningococci differ from serogroup A or C epidemics. Outbreaks move at different speeds, some peak quickly, others last years, a higher proportion of group B disease occurs in the under-5s...
It's hard for officials to decide how much we need to know without creating confusion and misunderstanding.
What elevated the latest controversy about MenzB above the ongoing guerrilla war between the health ministry and immunisation critics was that the findings came not from anti-immunisation "extremists" but from Auckland University's immunisation advisory centre. Its circular to GPs backgrounding the reasons for stopping the programme included several points which, to mere parents, seemed alarming:
* Fewer than half of infants aged 6 to 17 months were now protected against the meningitis strain targeted by MenzB.
* Post-vaccination immunity was measured in months rather than years (and this was evident from the trials).
* Most children would have antibody levels below the protective level seven months after their third dose.
The notice also said immunity declined less rapidly in older children.
Then the Herald revealed excerpts from a soon-to-be-published scientific paper co-written by Professor Diana Lennon, the Auckland paediatrician who headed the MenzB trials. The paper says that since the completion of the campaign, most children are unlikely to have any antibody protection against the NZ epidemic strain.
Most people assume vaccinations give long-term (if not lifelong) immunity and few parents could recall being told the vaccine would wear off within months. Both Lennon's and the immunisation centre's reports confirm that the vaccine's short duration was known before its mid-2004 launch. The knee-jerk reaction: parents and children were duped.
Many also took the fact that children were no longer protected to mean the $220 million vaccination campaign was a failure.
Lynda Williams, of Women's Health Action, said a lack of warning about the vaccine's limited lifespan had left parents with a false sense of security. "It could mean the difference between life and death if a parent saw signs of the disease in their child but did not seek medical help soon enough because they believed their child was still protected by the vaccine.
"The MenzB vaccination campaign was more about getting uninformed compliance than obtaining informed consent," she told the Cartwright seminar.
Now, Williams is making the same points about the cervical cancer vaccine, Gardasil. Information sent to GPs is not clear about its limitations, she says. "They are fudging the issue. Instead of saying it protects about 70 per cent of two viruses that cause cervical cancer, there's a vague statement that it protects against most cervical cancers."
She said the hype surrounding the HPV campaign, and the vested interests of the ministry and pharmaceutical giant Merck, would make it difficult to achieve truly informed consent.
"The vaccine is already being marketed as an anti-cancer vaccine. But ... it will take 20 years before such a claim can be substantiated because it takes around 15 years for cervical cancer to develop.
"How will all the other important messages around this particular vaccine be given _ such as the importance to practice safe sex and continue to have regular cervical smears?"
The ministry is still working on the information it will make available to help teenage girls and their parents reach informed consent on Gardasil.
Williams says critics will be watching to see whether anything's been learned from the MenzB campaign. Ministry's Jane O'Hallahan responds: "I challenge people in their assumptions that we somehow didn't provide enough information. We got historical levels of coverage _ that didn't happen on the back of no information."
O'Hallahan, who headed the MenzB roll-out, "absolutely refutes" suggestions that officials downplayed the vaccine's short protective span, fearing it would limit enrolments. "We were honest about it."
She says advice on duration was spelled out in the consent form brochure: "Protection is expected to last for a few years but the exact period is unknown."
That information remains valid, she says. "Our understanding around the length of protection hasn't changed."
She concedes that there's a gulf between what health professionals understand immunity to mean and consumer assumptions that vaccinations are for life.
"Since 2001, I forget the number of interviews I've given explaining that no vaccine is 100 per cent effective and this vaccine is not expected to give lifelong protection. It's a difficult message for people to pick up _ they assume it provides lifelong protection."
Victoria University conducted statistical modelling to estimate the vaccine's effectiveness. O'Hallahan says their most recent findings (not yet published) found no evidence of a waning effect 12 months after the third vaccination in the under-20s.
Although it was found during the campaign that babies needed four doses instead of three to reach the protection level, no significant differences had emerged in protection rates by age. "We understand from the data it provides good length of protection."
Still, there is an unbridgeable gap between Victoria's modelling _ which claims a 69 per cent effectiveness which did not markedly wane 12 months after the third dose _ and the Auckland follow-up findings that the lack of residual antibodies means vaccinated children are no longer protected.
Statistician Dr Richard Arnold says the Victoria team compared disease rates in the vaccinated and unvaccinated populations, adjusted for ethnicity, socio-economic circumstances and other variables. Their work confirmed the vaccine had a significant effect over and above the natural waning of the epidemic.
"Vaccination reduced the prevalence [of the strain] sufficiently to the extent that the organism was prevented from continuing [to spread]."
The modelling also suggests _ in contrast to the Auckland researchers' findings _ that the vaccine continues to be effective.
"The numbers aren't large enough to detect variation in effectiveness by age but we did have the power to detect waning after one year and we didn't see significant waning," says Arnold. "Whether antibodies are present [at sufficient levels] or not, the fact that the campaign took place provides protection."
Campaign critic Ron Law claims that, since 2006, the only deaths from the strain have come from the vaccinated population.
O'Hallahan says the overall picture (the total number of cases, not just deaths) is consistent with a vaccine which is roughly 70 per cent effective.
Diana Lennon _ who led the vaccine trials but was shut out of post-delivery evaluation _ says Victoria's mathematical modelling depends on assumptions and "what's fed in".
"The modelling's most significant finding was that the campaign prevented 54 cases and 1.7 deaths. That's nothing epidemiologically when we were talking about 6500 cases [over the 15-year epidemic].
"It's a modest vaccine. It's had an effect. Whether it's got ongoing effect is not clear. The only thing we do know _ or we assume _ is that you need antibodies to protect."
O'Hallahan says the Auckland University research "inflates the importance of waning antibodies".
She says it's important to remember that the rate of disease in 2001 of 25.6 per 100,000 was "panic mode" for a developed country. "Sometimes two or three children a day were being admitted to Auckland Hospital." The disease rate is now down to 3.6 per 100,000.
Professor Terry Nolan of Melbourne University, who peer-reviewed the Victoria team's data, agrees the vaccine was only moderately effective but says it contributed substantially to the decline of the epidemic.
"It's all very easy in hindsight to say the NZ Government has spent $200 million and only saved 54 lives _ it may have been five times that."
He is concerned that the vaccine has been shelved while the disease strain is still in the community.
Nolan says antibody levels are an "extremely imprecise" indication of protection. "Any vaccinologist would say the proof is in the performance of the vaccine in the field, which is what the Victoria analysis is doing."
Lennon stands by the antibodies data. "You have to have antibodies present to guess that the person or population would be protected."
After a group C meningococcal vaccination programme in the UK, there was a rise in meningococcal disease in young children who had waning antibodies, prompting a change in the immunisation schedule.
She says compared to recent vaccines, MenzB was old-fashioned _ but that's not a criticism. "This was a vaccine developed to control a large epidemic _ it wasn't about putting it into the immunisation schedule forever.
"That's probably a misunderstanding which could have been made more clear at the time of delivery."
Out at the coalface, the debate seems to have had limited impact. At the Turuki Healthcare clinic in Mangere, an immunisation nurse is annoyed that health professionals are learning more through the media about the reasons for winding-up the campaign than from official channels.
"The way they drip-feed you [information] is a bit annoying," says the worker, who did not want to be identified.
But after enduring years of sniping over the campaign, she says frontline staff have developed a tolerance for bad press. When the Herald publicised the vaccine's short lifespan, "I just rolled my eyes _ here we go again."
While there has been little feedback from parents of MenzB-vaccinated children, she says those receiving Prevenar, the new vaccine for pneumococcal disease, were confused.
"They think it's the same thing as meningococcal."
O'Hallahan says communication lessons learned during the MenzB campaign have been passed on to the HPV vaccine team. "You have to use multiple avenues and use every opportunity you have.
"It's clear people do want an in-depth conversation around vaccinations."
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HPV vaccine: the controversy
The HPV vaccine is one of the first vaccines designed to prevent a cancer caused by a virus (the Hepatitis B vaccine preventing liver cancer was first).
About eight in every 10 women who have ever been sexually active will have a human papilloma virus at some stage of their life. Normally there are no symptoms, and in 98 per cent of cases it clears by itself. But it can lead to pre-cancerous cells which may develop into cervical cancer, a process that can take 10 to 20 years.
Thanks to pap smear tests ushered in after the Cartwright Report, deaths from cervical cancer have plunged from 180 10 years ago to around 60 each year. Around 160 cases are diagnosed each year.
The HPV vaccine offers an additional weapon to screening, and Prime Minister Helen Clark _ who, as Health Minister, launched the cervical screening programme in 1989 _ has committed $177 million in funding over five years.
The chosen vaccine, Gardasil, protects against four types of HPV _ two which are responsible for about 70 per cent of cervical cancer, the other two for about 90 per cent of genital warts.
Clark expects it will, in time, save about 30 lives a year. Gardasil is claimed to be at least 97 per cent effective against the two types responsible for most cervical cancers. Three doses are needed.
Advice given to Clark is that it needs to be given before a girl is sexually active to be most effective. But its pre-election roll-out is not without opposition.
In the United States, health agencies have been forced into damage control after newspaper reports linked Gardasil to fainting, paralysis and the death of a 19-year-old two weeks after vaccination. Those reports have been picked up in New Zealand.
Last month, the US Centers for Disease Control and Food and Drug Administration moved to reassure consumers and health professionals that Gardasil was "safe and effective".
Oncologist Dr Maurie Markman, an expert adviser to the US online journal Medscape, explained: "The fact that an event happened after vaccination does not mean that it happened because of the vaccination."
Diane Harper, of New Hampshire's Dartmouth Medical School, who helped develop the vaccine, told the journal Gardasil was "a good vaccine and it is generally safe".
However, women would still need regular smear tests to avoid the risk of developing cervical cancer, said Harper. "The data so far shows that vaccination is effective for five years, but it is still unknown whether boosters may be needed. The true value of the HPV vaccine will be to provide women with a greater reassurance that their future pap screens will more likely be normal."
She feels the importance of continued screening had not been made clear to the US public, where it had been overshadowed by aggressive and inappropriate promotion of Gardasil by pharmaceutical giant Merck.
Interviewed by Radio New Zealand, Harper said the vaccine had not been tested for effectiveness in young women and there were questions about how long it will last. For 12- and 13-year-olds, it may have worn off by the time they become sexually active.
Harper also challenged the wisdom that the vaccine had to be given before women become sexually active to be most effective. She said it was just as effective after a woman became sexually active, even if infected with an HPV.
Earlier, she told Medscape: "Pap screening is still the only proven method we have for cervical cancer prevention. We don't know how long the vaccine will protect a woman from HPV infection, and the vaccine does not protect against all types of HPV infection that cause cervical cancer.
"In the end, regardless of whether a woman chooses to be vaccinated or not, the take-home message is to start and continue pap screening throughout your life."
