082 - An Attempt to Increase Resistance to Pertussis in Newborn Infants by Immunizing Their Mothers During Pregnancy

With vaccine-preventable diseases, young children are often most at risk of serious health impacts or death; the younger, the higher the risk. At least, this is true of whooping cough, which had mortality rates of 26-55% in the 1930s among infants less than a year old.

However, some observed that newborns up to six months old seemed to have some resistance to some diseases—diphtheria, polio, measles, and scarlet fever, for example—especially when the mother had resistance of her own, such as immunity from having had the disease. So it seemed like the mother was transferring her immunity to the infant, probably through the placenta.

So John Lichty, Betty Slavin, and William Bradford thought it might be wise to take advantage of this transfer to give newborns more resistance until they could be vaccinated themselves around 6 months. In this study, they try immunizing mothers during pregnancy and then observing the immune response in mother and infant.¹ This was building on previous work in humans and animals with the same or other diseases, to some extent.

So they selected healthy women with normal pregnancies in obstetrics departments of Rochester hospitals, assigned them randomly to be immunized or be a control, using Sauer's whole-cell pertussis vaccine from Eli Lilly. No placebos, so no blinding of patients. They did separate observations of mothers and infants based on whether mothers had had pertussis before; i.e. history or no history. So they had four study groups: no history or vaccine, history but no vaccine, vaccine but no history, and both history and vaccine.

The way they measured immunity was a bit unusual: opsono-cytophagic index. They took blood from subjects, mixed it with dead pertussis bacteria, and observed how many dead cells the white blood cells gobbled up. They compared subjects based on the number of white cells that ate at least 20 dead bacteria; the "index" value. Presumably the immune status would affect how likely the white cells were to eat the bacteria. There was blinding in this test somewhat: the examiner counting the index didn't know the status of the subject from whom the blood was taken, so as not to be biased in counting.

Results

In total, there were 28 women immunized and 22 as controls. They observed in most groups, most infants had a lower index than their mothers; the exception was the vaccine+history group, in which a third of infants had a higher index.

I made a graph showing the values for the four groups, mothers and infants (in mothers' cases, after the vaccine, when relevant):

Opsono-cytophagic index for mothers (post-vaccine) and their infants; error bars are standard deviations reported in the study.

Overall, looking at the error bars, it doesn't seem like there's much significant difference anywhere. But looking at trends, two things stand out: infants from mothers with no history or vaccine seem lower than from mothers with either, and with both it's highest. Second, the difference between mothers and infants is largest with neither history nor vaccine, lower and similar for history or vaccine, and mothers and infants are closest with history plus vaccine.

The authors looked at a couple other things too. They observed some of the infants before they had nursed and then again after nursing for one week, to see if the colostrum affected the immunity at all. It didn't seem to make a difference.

Secondly, they looked at some clinical data for other patients; specifically, of 31 infants that died from pertussis. Eighteen of them died before 6 months of age, and 13 after. Of those that died younger, 28% of their mothers had had pertussis before giving birth; of those that died older, the number was at least 54%. Sample sizes were pretty small, but it suggests that mother's immunity does have a protective effect for the infant up to 6 months. Seems like just correlation though.

The authors concluded that vaccinating mothers seemed to help. Comparing each infant's index to mother's, the group with neither immunity had only 50% the index in infants compared to the mother; with either vaccine or history, that number went up to 75%; and with both, 100%, almost identical index. So perhaps an additive effect.

Overall, not a very rigorous study, but suggestive. Later articles were somewhat critical of the study, perhaps explaining the weak results:

"Lichty, Slavin, and Bradford attempted, as they put it, to increase resistance against pertussis in newborn infants by immunizing the mother during pregnancy. They confessed their failure. An analysis of the data revealed the following facts: The injections were given at two week intervals in the last six weeks of pregnancy. The total dose administered was 20-25 billion [cells]. Thus the dose was inadequate and too late for antibody formation which reaches its climax between one and two months after the last inoculation. The test for immunity which they employed, cytophagocytosis of the blood, has distinct limitations and has been abandoned by them in favor of mouse tests. Their figures showed no increase in cytophagocytosis of the inoculated mother's blood. Granted the validity of the test, they found no increased immunity in the mother, so that there were no antibodies transferable to the baby through the placenta."²

Even later, though, most studies citing this one seemed to focus on the safety aspect (which I forgot to mention above): of the mothers in the vaccinated group, almost the only side effect was a sore arm that wasn't bad enough to interfere with daily life. One woman had a systemic reaction with nausea and vomiting. Here's an example of a mention:

"Although phase 1 studies of maternal immunization with Tdap are in progress, studies many decades ago with whole-cell pertussis vaccine administration late in pregnancy resulted in high levels of pertussis-specific antibodies in infants and no safety concerns."³

Sometimes I wonder if people actually read old studies before citing them, but I guess usually it doesn't make much difference.

References:

1. Lichty, J. A., Slavin, B. & Bradford, W. L. An Attempt to Increase Resistance to Pertussis in Newborn Infants by Immunizing Their Mothers During Pregnancy. J Clin Invest 17, 613–621 (1938).

2. Cohen, P. & Scadron, S. J. The placental transmission of protective antibodies against whooping cough: By inoculation of the pregnant mother. JAMA 121, 656–662 (1943).

3. Healy, C. M., Rench, M. A. & Baker, C. J. Importance of Timing of Maternal Combined Tetanus, Diphtheria, and Acellular Pertussis (Tdap) Immunization and Protection of Young Infants. Clin Infect Dis. 56, 539–544 (2013).

013 - The Opsonic Index as a Guide to regulate the use of Vaccines in the Treatment of Disease

This paper seems to be near to the inception of immunology, obviously an important area of research into the mechanism and function of vaccines. The authors report on work done by a number of researchers (mostly women, interestingly) evaluating the opsonic index, mentioned here before.

To recap: the opsonic or phagocytic index is a measure of the activity of white blood cells in consuming bacteria they encounter.

Research previous to this paper had discovered that the increased activity of the white blood cells (aka leukocytes) of vaccinated animals was not something inherent to the cells themselves—isolated leukocytes from unvaccinated animals had the same activity. Rather, the increased activity came from some other component of the serum of the animal (the liquid, cell-free portion of the blood). A.E. Wright referred to this serum element as "opsonins," which bind to the pathogen and induce phagocytosis, that is, uptake by white blood cells.

According to Wright, who developed the opsonic index method, determining this index value is important for administering vaccine therapy, because too high a dose can actually reduce a person's immunity to a pathogen.

The way this opsonic index is determined is to take equal amounts of bacteria, blood cells, and serum and mix them together, incubate for 15 minutes, then examine them under a microscope and count how many bacteria each leukocyte has taken up into itself.

The authors here describe a number of factors that must be controlled to get an accurate opsonic index value; failure to control them can introduce significant artifical variation. Such factors include number of leukocytes counted from each sample (at least 50 is important, up to 150; speaking from experience, that sounds like a seriously unpleasant experience for the person doing the counting, staring into a microscope for so long; especially since it is also important for just one person to do all the counting, since different people count the numbers differently and induce more variation), and slight variations in mixture proportions can introduce variation too. Because of these difficulties, it often took so long to finish a counting that the vaccinator had to go ahead and treat the patient before actually getting the results.

There was some investigation into the nature of these opsonins, too. Those from unvaccinated serum were more vulnerable to disruption by heating than those from vaccinated, and the former seemed to bind more generally—they could be titrated or removed from the serum using common "complement absorber" compounds—whereas the elements from vaccinated serum were more heat-stable and only bound well to the pathogens that had been vaccinated against. The latter, they referred to as "antibodies." We know more about these elements in modern times, of course, as members of the innate vs. adaptive immune systems.

The authors also report a number of trials of vaccine therapy against a variety of pathogens, using opsonic index measurements to inform the therapy. In most of the cases it didn't seem to help very much, and the index readings were inconsistent, so it didn't seem as useful as Wright made it out to be.

Citation: Park, W. H. & Biggs, H. M. The Opsonic Index as a Guide to regulate the use of Vaccines in the Treatment of Disease. J Med Res 17, 77–88 (1907).

010 and 011 - On the Treatment of Acne, Furunculosis, and Sycosis by Therapeutic Inoculations of Staphylococcus Vaccine

Next up is a pair of articles by the same researcher that helped develop the antityphoid vaccine (009), Almroth Edward Wright. Apparently he is quite a character, worth reading about; he predicted the rise of antibiotic-resistant bacteria and was a big advocate of preventative medicine.

In this pair of articles, Wright was attempting to develop a therapeutic (rather than preventative) vaccine against Staphylococcus, a common cause of skin infections such as boils (aka furunculosis) and hair follicle infection (sycosis). The preparation of the vaccine was similar to that of the antityphoid: grow up the bacteria, kill them somehow, and inject this into the patient. Often he used bacteria cultured from the patient’s own infection.

The first paper is a series of case reports, with some in-depth data and graphs(1). The second is another series of descriptive case reports of patients treated with this therapy(2). In each case, it appeared to help the patient’s current problem, but each patient seemed to suffer recurrences, the same or different, pretty often.

One interesting aspect to these reports is the measurement of phagocytic/opsonic index, a measure of how well the treatment increased the immune response. It did seem to increase after the vaccination. Other articles citing these papers give some more details:

Wright and Alexander Fleming developed technique called opsonic/phagocytic index to measure levels of antibodies against pathogen.

"This was considered necessary because by giving too large a dose of vaccine one could lower the antibody level in what was called a 'negative phase' to such an extent that the patient might become worse because he did not have a sufficient margin of resistance to safeguard him against any generalization of the infection....Fleming and his colleagues carried out no less than 16,000 opsonic tests in one year, each of which required half an hour."(3)

"Here again, a lack of adequate controls confounds the analysis. Wright's methods for measuring opsonizing activity were criticized by the renowned biostatistician Karl Pearson who deplored his cavalier indifference to statistical tests of significance: Pearson concludes one paper critical of Wright's data analysis with the exhortation 'Statistics on the table, please!'"(4)

"No adequately controlled clinical trials were undertaken to demonstrate the effectiveness of these forms of therapy."(5)

Sums it up pretty well, I think: not great quality. I hope to learn more about vaccine therapy in future reading though.

References:
1. Wright, A.E. Notes on the treatment of furunculosis, sycosis, and acne by the inoculation of a staphylococcus vaccine,: and generally on the treatment of localised bacterial invasions by therapeutic inoculations of the corresponding bacterial vaccines. The Lancet 159, 874–884 (1902).

2. Wright, A. E. On the Treatment of Acne, Furunculosis, and Sycosis by Therapeutic Inoculations of Staphylococcus Vaccine. Br. Med. J. 1, 1075–1077 (1904).

3. Hare, R. The scientific activities of Alexander Fleming, other than the discovery of penicillin. Med. Hist. 27, 347–372 (1983).

4. Burke, D. S. Vaccine therapy for HIV: A historical review of the treatment of infectious diseases by active specific immunization with microbe-derived antigens. Vaccine 11, 883–891 (1993).

5. Stein, D. S., Timpone, J. G., Gradon, J. D., Kagan, J. M. & Schnittman, S. M. Immune-Based Therapeutics: Scientific Rationale and the Promising Approaches to the Treatment of the Human Immunodeficiency Virus-Infected Individual. Clin. Infect. Dis. 17, 749–771 (1993).