Respiratory viruses: ‘a quaking bog’

Issue: October 2011

I sometimes wonder if we are still in a quaking bog with respiratory viruses. “By no means,” I hear virologists, epidemiologists and clinicians with a special interest in viral diseases screaming. Yes, almost countless numbers of viruses causing respiratory infections have been identified, the symptoms and signs — though much overlapping — have been characterized. Steps ahead in antiviral medication have been taken, and measles and influenza vaccines are among the crown jewels of disease prevention.

Heikki Peltola, MD

But, take another view. Virtually every child experiences one to three respiratory infections a year, and this is especially true for younger children and those in day care. Only a few of those episodes (caused mostly by rhinoviruses or a mixed etiology) are dangerous, but imagine the child’s feelings of ill-being, his/her cry, the parents’ concern, the family members’ sleepless nights — and then, the same infection in another child or a parent. Most otitis media cases commence from a viral infection, and not infrequently, someone in the family setting develops a more serious complication, such as pneumonia. And, if a child is sick, one of the parents has to stay at home. Count all of these events together, and imagine the total cost to the society. The monetary price is almost unaccountable, let alone the costs that cannot be expressed in dollars or euros.

Viral transmission

Books have been written on how to cope with the problems caused by viral respiratory infections. To some degree, we can prevent those by social segregation, by better and individualized approach in kindergarten — own handkerchiefs and towels, separate food distributors, no tooth-brushing — but do we follow these rules? The answer is “no” because it is not easy to put those in effect in the everyday practice, where manpower is restricted. Perhaps the easiest way to lower the incidence of respiratory infections would be to reduce the size of the child groups. However, the shortage of personnel is a problem, as the costs are deemed too high. But, I bet the price wouldn’t actually be too high if you sum up all of the costs listed above. Years ago, it was shown that the risk for acute otitis increased 32-fold when the child started day care in the same indoor location with tens of other children of whom somebody always had a respiratory infection in its most spreading phase.

Another study by Louhiala and colleagues found the adjusted RR for pneumonia being 9.69-fold (95% CI, 2.31-40.55) among 1-year-old children who attended day care. The proportion of pneumonia attributable to day care was no less than 85% (95% CI, 57-98). Importantly, family day care with considerably smaller child groups essentially did not increase the risk. If the health of adults would be endangered at all near these levels seen in children, demonstrations on the streets would be likely, and quick changes in legislation ordering the reduction of groups would be put soon in effect.

As rhinoviruses are the No. 1 causative agents in banal respiratory infections of children and adults, the industry’s (which has the big money) interest in these agents has been surprisingly meager. When asked, the usual response is that the 200 or so different types of rhinoviruses pose a too formidable problem, even to “Big Pharma.”

Vaccines in waiting

Well, the monster no doubt is there, but in the 1970s, a general thinking was that systemic antivirals would be very difficult to develop because of the complexity of making an agent that would penetrate a living cell and kill the viruses without destroying the cell as well. Then, thanks much to the AIDS epidemic, we now have many antivirals that do exactly that against HIV and some other viruses — but not rhinoviruses.

Similarly, one wonders about new vaccines against commonplace respiratory infections. Killed respiratory syncytial virus (RSV) vaccine of the 1960s (which proved dangerous) cast-long shadow to the vaccine development against this particular agent. But still, why has a next-generation RSV vaccine been looming “around the corner” now for decades? And not a whisper has been heard of a rhinovirus vaccine.

Meanwhile, other types of industry products are sold in abundance. Approximately 30% of a countryside pharmacy’s income in Finland arrives from vitamins; variable “flu medicines” are administered to almost all people with coryza; coughing patients are given antitussives; and in many countries, the budget around homeopathy exceeds that of all antimicrobials counted together. All of those agents have no or very little solid data behind their wide use.

Occasionally, a glimpse of light is penetrating the stagnant, stale air. The role of vitamin C has been discussed up and down for decades, but look at the data on the trace element zinc. Unlike iron or vitamin A, it has no tissue reserve but rapid turnover. Red meat is the main source of nutritional zinc, but because meat is expensive, 30% of the world’s population suffer from zinc deficiency of some degree.

An analysis of 13 placebo-controlled trials on zinc lozenges found three more-or-less well-done trials using the dose of zinc acetate of at least 75 mg per day. The pooled result was that the difference was days, not hours, in the duration of cold — by no less than 42% (95% CI, 35-48). Other zinc salts with this dose condition (five studies) shortened the symptoms and signs by 20% (95% CI, 12-28). The paper leaves the reader with several questions, but at least it suggests that inexpensive mitigation of these trivial but so irritating diseases might hide in the horizon if looked for. Keep your eyes open.

But, I repeat, where is the rhinovirus vaccine?

For more information:

Hemilä H. Open Respir Med J. 2011;5:51-58.

Louhiala PJ. Am J Public Health. 1995;85:1109-1112.

Heikki Peltola, MD, is professor of infectious diseases and head of pediatric infectious diseases at the University of Helsinki, and Helsinki University Central Hospital, Helsinki, Finland. He can be reached at heikki.peltola@hus.fi. Dr. Peltola is also a member of the Infectious Diseases in Children Editorial Board. Disclosure: Dr. Peltola serves as a clinical scientific consultant for Serum Institute of India Ltd., and has received lecture grants from other pharmaceutical or vaccine companies.

Follow the PediatricSuperSite.com on Twitter.